A mod is a festival of Gaelic language arts and culture in Scotland. The Mod (full name, Royal National Mod) is an annual mod, first held in 1892. It has been compared to the Welsh National Eisteddfod.
MOD is a computer file format for certain music files created with tracker software.
Internet slang for moderator, a person on an Internet discussion forum who can edit or otherwise change the state of other users' comments, similar to (though less powerful than) sysops.
Case mods; modifications made to a computer in order to improve its appearance.
A Modchip, a device used to play import games or circumvent the digital rights management of many popular video game consoles