all the iron tips sold on geekhackers are spades/chisel tips except for the fancy ones. in particular, i can get you anything from the edsyn catalog, including weird hooked tips, specialized SMT crown tips, and a couple of extremely nice solder cup tips (HIGHLY recommended for hand soldering of qfps and soics)
anyway, the "standard" tips for all the irons I sell are:
small: ~1mm spade
medium: ~2mm spade
large: ~3mm spade
remember, soldering is NOT about changing working temperature but about changing the amount of power transferred to a joint in order to achieve working temperature as quickly as possible without exceeding it. the determinant of power transfer is SURFACE AREA! repeat it! live by it! die by it! (no, not that last one. don't hurt yourself. soldering irons are hot).
but seriously, soldering is about setting a working temperature (rule of thumb is 350C for leaded, and 450C for unleaded), and then manipulating the size of your "thermal channel" or surface area in contact between the iron tip and the joint in order to reach that working temperature quickly on _both leads of the joint, and the solder_ without exceeding that temperature by enough to damage anything.
that's it! recite it while you're soldering and it will make your life much easier