on the atmega8/168, on the $50 robot board, you can break out PB0, PD5, 6, 7, PB6, 7 safely.
You can also breakout PC6/reset and the programming pins, but with those you really have to know what you're doing or you could screw up the chip.
[img width= height=]http://www.sparkfun.com/tutorial/BeginningEmbedded/2-MicroProgramming/ATmega168-Pinout.jpg[/img]