Pugsy has produced a package including cheats for MAME as well as a number of machines using software lists (such as consoles and computers). This has been updated to include some newer additions since the last release of the package and fix some bugs which became non-functional due to changes in MAME.
Quote: Here is the cheat collection update for the latest MAME 0.186 (due release tomorrow). The highlight of this release is that it now contains cheats for 1929 games from the PSX softwarelist, I've collated the cheats from various GS/AR lists and converted them into XML format for ease of use.