Just because you walk out the door of your favorite brewery doesn't mean you can't take the good times with you. The majority of Colorado's craft brewers sell growlers -- 64-ounce brown glass bottles, for the most part, topped with a screw-off cap. Most will sell you the vessel for anywhere from $5 to $10, which you can then bring back for a fill, usually around $8 to $18, depending on the beer. But as great as growlers are, most don't keep beer fresh for very long. In fact, those screw-top caps mean your beer will likely be flat within a day or so.

And because of their shape, growlers are unwieldy and not particularly practical, which is why a few brewers, especially those that don't bottle or can their beers, are experimenting with other ways to sell beer to go. Some are selling a limited amount of these containers as a way to raise money and offer VIP perks.

Here are five cool ones.

5. Nalgene Bottles

Equinox Brewing in Fort Collins sells eighty-ounce Nalgene bottles that won't shatter like glass and are BPA free. Like cans, the bottles can travel places glass can't, and they are topped with a more air-tight lid.

3. Stainless Steel Growlers

Bonfire Brewing in Eagle sells insulated 64-ounce stainless steel growlers. There were 85 sold in the original batch, at $45 each (beer included), on a first-come, first-served basis. Stainless steel keeps the beer colder longer and lid keeps it fresher. Call ahead to make sure they have them in stock.

3. Forty-Ounce Canteens

Wit's End Brewing in Denver sells stainless-steel forty-ounce canteens that you can buy one for $20 (including your beer) and refill it whenever you want for $9. (Between fills, you can use it for water or whatever other liquid makes you happy.) A heavy-duty o-ring should keep the beer fresh for at least two weeks. "And besides," says brewery owner Scott Witsoe, who won Westword's Best New Beer Idea To Go this year, "we couldn't pass up on the irony of a craft brewery selling beer in forties."

2. Groupie Growlers

Caution Brewing began selling 32-ounce Groupie Growlers for $40 when it opened its new taproom last weekend. The aluminum canteens include one free fill and they get you VIP status, including invitations to exclusive tappings, a chance to brew with the Caution team and $6 refills through 2012; Caution only has 100 available.

1. Half-Size Growlers

TRVE Brewing, which hopes to open in the next few weeks, will use glass growlers, but they'll be half the size of a traditional growler because as owner Nick Nunns points out, "When's the last time you ever finished a whole 64-ounce growler by yourself?" If you're that thirsty, get two of them and try two different beers. "You can always save that second growler for another night as well, without having to worry about it skunking." But getting that second growler might not be easy because Nunns is actually starting a limited-membership growler club similar to Caution's so that growler customers don't drink him and his tiny, three-barrel brewing system, out of beer.

The "Growler Cvlt" allows members, who pay a $50 yearly fee ($25 for the second), to get their first five fills for free and then fill up any time after that with any beer for just $7. There are only 266 growlers total, each one numbered and signed by Nunns and Snowblinded, the artist who drew the head-banging illustrations on the side.

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