8/16/32U2 only come in QFN and TQFP
Get the TQFPhttp://parts.digikey.com/1/parts/1846461-mcu-avr-8k-flash-16mhz-32tqfp-atmega8u2-au.html
Then you could get a 32pin TQFP to DIP adapter but you will need to solder the part onto the PCB... There are lots of different ones here, they are on the expensive side, I'm sure you will find cheaper somewhere on the net, This kind of part only costs $0.3ea to produce in volume, so keep this in mind...http://www.epboard.com/eproducts/protoadapter1.htm
When you order, better get a 1 spare of the PCB and uC unless your comfortable with fine pitch soldering like this
When you are going to solder to the pcb, get a really fine tip for your soldering iron, really thin gauge solder, and start by tacking down pin1, and then pin17 to get it straight. Once lined up, then solder all the other pins and check for shorts before firing up.
if you've got money and no timehttp://parts.digikey.com/1/parts/409179-socket-adapter-tqfp32-sa636.html