Right click on spinners to zero them. Handy for lining up a load of verts if you haven’t got the ‘vertex placer’ script installed, or making sure objects are in the centre of the world. Don’t know how well known that is, but I keep forgetting it. Vertex placer can be found here-

http://www.ricoholmes.com/

If you’re trying to use metric units, don’t just change the setting in the ‘unit setup’ box, also set it in the ‘system unit setup’ sub menu, or it’ll think 1 unit=1inch still.

Always check the snap settings when swapping between viewports. I’m ALWAYS forgetting to swap between 2.5d in planar views and 3d in perspecitve or user views. (although I’d rather the settings were per viewport, what’s the point of a 3D snap in a 2D viewport).

Use the Renamer utility if you’ve got a lot of objects to rename. It’s got lots of handy options for incremental naming etc.

There’s a Swami Lama script for converting copied objects into instances called ‘instance-o-matic’. http://www.scriptspot.com/start.htm

Check out Chugnuts Unwraptools for a bunch of handy tools for um uvmapping. The ones for aligning a load of uvs are great as are the ones for evenly spacing them.

http://www.chuggnut.com/scripts/unwraptools/unwraptools.htm

Lots of others that I can’t think of now.