Scotland's SNP government, led by Alex Salmond, may be the independence movement's biggest voice, but there are plenty of others with ideas on how the nation could go-it-alone.

Ahead of the referendum on 18 September, here's a look at some alternative political visions for Scottish independence.

1. Scottish Greens

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The Scottish Greens are the only pro-independence party other than the SNP with seats in the Scottish Parliament (they've got two) - and they don't like being called nationalists.

Be informed Go to the BBC's Scotland's Future page for analysis, background and the latest news on the Scottish independence referendum.

The party says this debate has little to do with identity and patriotism and everything to do with getting rid of a Westminster parliament "beholden to big business".

Unlike the Scottish government, the Greens say keeping the pound should be a short-term option, arguing Scotland would only be truly economically independent with its own currency.

The party also criticises the use of "tired old slogans about 'Scotland's oil'", saying it's time to break the nation's dependence on big energy, by supporting a wider range of ways to make electricity.

The Greens - who say businesses care more about an educated workforce than tax cuts - envisage a welfare state which lets people make their own decisions and allows small firms to thrive.

And despite the SNP reversing its policy against Nato membership, the Greens say this move would, "amount to a request that other countries deploy these obscene weapons on our behalf".

2. Wealthy Nation

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"Conservatives don't need to be Unionists", or so goes the mantra of this right-of-centre, pro-independence organisation.

While the notion of a group which on one level could be described as "Tories for Independence" seems surprising, Wealthy Nation - fronted by author and historian Michael Fry - says the biggest risk to an independent Scotland is the "the dead weight of managerial socialism".

Wealthy Nation, a collection of business people, academics and others, which describes Britain as a failed state, says Scotland should adopt more of a Thatcher-esque free market approach, with less government interference, less tax and more choice in health and education.

The group argues that, rather than being held back by the brand of socialism offered by some, Scotland should look to the example of former Communist bloc countries like Slovakia and Slovenia, whose approach to de-regulation, de-taxation and de-centralisation has led to economic growth not seen in Scotland for 100 years.

As Michael Fry puts it himself: "The key to future happiness lies not in the redistribution of wealth - the key to future happiness lies in the creation of wealth."

3. Scottish Socialist Party

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In sharp contrast to Wealthy Nation, the SSP has been arguing the case for a monarchy-free, Scottish socialist republic, although the party is far from the political force it once was.

The socialists want to end the "offensive" practice of making MSPs swearing their allegiance to the Queen and want Scotland to break free from the "suffocating stranglehold of the British state" by creating a country which stands up for ordinary people.

As well as abolishing the royal family, the SSP wants a nuclear-free Scotland - outside Nato - and military spending cut to Republic of Ireland levels.

And they want Scotland's proposed constitution drawn up by an elected assembly, as well as seeking a new relationship with the EU to "safeguard Scotland's independence."

The SSP also seeks electoral changes, including an end to first-past-the-post voting, in favour of PR, and give homeless people and prisoners the right to vote, as well as greater use of referenda to allow ordinary people a say in controversial decisions.

The party's policies are very similar to those put forward by Tommy Sheridan's breakaway Solidarity party.

4. 'The Highland Two'

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The SNP's decision in 2012 to end its decades-old opposition to Nato membership caused a lot of strife within the party.

Westminster leader Angus Robertson said the fresh approach was needed ahead of the referendum - although part of the argument for Nato within the SNP rested on a pragmatic calculation that most voters favoured membership.

The change was accepted, but not everyone got over it and Jean Urquhart and John Finnie, both MSPs for the Highlands and Islands, quit the party as a result.

The pair said they could no longer be in a party which wanted to associate with a "first strike nuclear alliance", and remained in parliament as independent members.

Aside from Nato though, Ms Urquhart and Mr Finnie continue to support the case for independence.

5. Radical Independence

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More of a campaign than an organised political party, Radical Independence, which has signed up actor David Hayman as its figurehead, also champions a left-wing future of Scotland.

Its starting point is that, after 30 years, the British state has failed to live up to expectations and now "trembles" at the thought that independence may happen.

The organisation wants more equality among citizens, as seen by other small, independent nations, while abandoning 30 years of exploitation, which it says make a few people rich.

In what it describes as a fine Scottish tradition, Radical independence states: "Let us gift ourselves an economy where we make and create. Let our creativity make working people prosperous. Let prosperous people sustain a great welfare state. Let that state end the fear that comes with insecurity."

6. Dennis Canavan

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Dennis Canavan has never been afraid of ploughing his own furrow, having come out batting for independence after service as a Labour MP and independent MSP.

He also wants Scotland to adopt its own currency after independence, saying it would give the nation more flexibility, more freedom and a wider range of economic levers.

When it comes to the Royals, Mr Canavan also wants a national referendum on who should be head of state in an independent Scotland - a view also held by Scottish Children's Minister Aileen Campbell - adding that he'd like to see someone elected to such a position.

Mr Canavan's comments, which are are at odds with SNP policy, are interesting because he chairs the official campaign for independence, Yes Scotland.

He points out they are personal views, and adds that Yes Scotland is a democratic movement which embraces a range of views while not indulging in "control freakery".

7. Labour for Independence

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This group was set up by frustrated Labour member Allan Grogan, who argues the party is wrong to automatically take a pro-Union stance.

Labour for Independence says it's committed to policies including scrapping the minimum wage in favour of a "living wage" which would remove most people from the poverty line and save money on tax credits.

The organisation also wants a simplified version of the welfare system, with removal of means testing on disability allowances.

It also suggests that nationalising or re-nationalising energy, transport and care work, would see the profits otherwise made by private companies put in the national coffers to pay for better services.

Labour for Independence claims to be growing in the Labour Party. Scottish Labour though - which is firmly in support of the Union - says the movement lacks any real support from within its own ranks.