http://dangerousprototypes.com/forum/viewtopic.php?t=170

It looks like the PICKIT2 uses a small boost converter.

http://www.oshonsoft.com/picprogprousb.html

USB Pro PIC-PIC18-PIC16-AVR Programmer 

USB Pro AVR Programmer

Serial Port Pro PIC-PIC18-PIC16-AVR Programmer 

 http://www.oshonsoft.com/picprogproserial.html

Serial Port Pro AVR Programmer

 

http://www.woe.onlinehome.de/proj_gif/prg2051.gif

 

http://hw-server.com/obrazek/atm_sch_.gif

http://chaokhun.kmitl.ac.th/~kswichit/easy1/ws1s1.gif

 

http://images.batronix.com/graphics/circuits/mc_prog_b_sch.gif

 

http://www.next.gr/uploads/41-6d10a5dc66.png