Here is a suggested list of tools to keep in your toolbox.  Its what I've found I've needed over the years.  Another good idea is to keep all your old parts handy, because you never know when you'll need one.

~ full set of allen wrenches (standard)
~ strap wrench
~ needle nose pliers
~ wire snips
~ vice grips 
~ 7/16 crescent wrench
~ 9/16 crescent wrench
~ telfon tape
~ blue locktite
~ dental picks
~ 1/4" 12 sided long necked socket wrench (for the ASA)
~ Valve Tool
~ Dow33