I' m hoping to soon get a little rotary tool, I think that would be very handy (similar to a Dremel Tool).  They aren't very expensive at the  local market.  Finaly for more air tools see my section on bodywork tools.
Air dusters, you'll have a couple of these if you own a compressor, they can be handy.  I couldn't find a cheap tire inflator anywhere.  It was cheaper to buy this crappy air set shown than just a tyre inflator.  It has a degreaser gun (I've never used it, the tin of degreaser I've included is incredibly cheap and better), the tyre guage is very inacurrate but works.  The spray gun I've used, and it works kinda ok.  I wouldn't try painting a car with it though.
D/A Sander.  This works well,  but it's bloody hard on the compressor.  It works the 16cubic foot compressor constantly, it JUST runs it.  A much better option would be a cheap chinnesse electric D/A sander.  I try not to use it to much, it's just to hard on the compressor.  Don't bother buying one of these unless you have a massive industrial 3phase compressor....  The sanding disk shown just sticks on like a sticker.
Air grease gun, very, very handy, if it ever dies I'll replace it with a standard mechanical grease gun, that way you don't need a compressor to use it ...  Sometimes it's a pain having to drag an air hose around for something like this (especialy if you want to use the grease gun at a friends house).
Air chisel will effortlessly shear most rusted studs, or anything else that needs a heavy duty chisel.
Air tools.  I  don't have a huge amount of air tools.  The rattle gun is very useful, I've also found that tube sockets are very handy with it.