I have an 858D hot air station that is useful for all sorts of stuff.
A caliper is a great tool if you don't have one.
I also have a KPS305D benchtop power supply. I haven't had it long, so I can't vouch for durability, but it works great so far. Just dial in the voltage you want, and it does it.
My soldering iron is a Weller brand WLC100. It does everything I need it to.
A solid dremel is one of the best tools you can have. Dremel brand is the only way to go. A variety of bits can come in useful too in ways you wouldn't expect.
Some other ideas:
Extra pointy soldering iron tips
Thin solder
Good pliers
Wire strippers
Kit of tiny screwdrivers
Nintendo screwdriver bits
Assorted colors of stranded wire
Assorted sizes of magnet wire
If you order on ebay, it's a good idea to get a variety of plugs, switches, leds, resistors, capacitors, tact buttons, perfboard, etc from China before you need them. It's just nice to have all sorts of things like that laying around.