I use this: http://www.amazon.com/GearWrench-85035-35-MicroDriver-Set/dp/B0062FSAVI

It's hard to say without knowing exactly what you're going to be doing, since it varies so much job to job. I work on the MRO side of things doing c-checks on commercial birds, and on a day to day basis my most used tools are just your basic hand tools and my 12V drill. However I have picked up some other stuff along the way that has proven invaluable:

• Skin Sppons, they're really good for cutting sealant and all prying when there's just a little bit of a gap
• This little ratchet, some weeks I use this thing more than my regular ratcheting screwdriver or 1/4" ratchet, it helps out in tight spots
• Brass Punches
• Spline sockets, it will really vary aircraft to aircraft how much you really need these. Craftsman has decent cheap sets, they call them universal sockets or something.
• Ignition wrenches, there's lots of shitty little hardware
• Headlamp

That's all I can really think of at the moment, don't worry about having every possible tool you can think of before you start. There's no sense in spending a bunch of money on tools you won't end up using. It's much easier to figure out what you need to fill in gaps once you start rather than trying to guess now. No one is going to expect you to have everything right away and it sounds like you have a good start already.