Note: this post is from 2007, outbound links may be broken.
Atom Splitter Audio releases Games and 8-Bit Kit Volume 2 and Digital Effects Volume 1
Game and 8-Bit Kit Volume 2 includes samples of retro style blips, zips, effects and leads which are similar to the classic chiptune style used in retro video game music. The sounds are not sampled from any hardware and are all original and royalty free to use in your music productions. The pack contains 79 .wav sounds and is 13MB.
Digital Effects Volume 1 offers digitally made sound effects, with zaps to real world sounding effects. This sample pack is royalty free to use in your music, and includes 32 samples in .wav and the size is ~10.2MB.
Visit Atom Splitter Audio for more information, and links to download these free sample packs.