YACC: Yet Another Compiler Compiler.
YAST: Yet Another Setup Tool.
YAPC: Yet Another Perl Conference.
YaBB: Yet Another Bulletin Board.
YABA: Yet Another Bloody Acronym (see TLA).
YAUN: Yet Another Unix Nerd.
YAAP: Yet Another Ascension Post (an announcement of a win at NetHack).
This jargon is also used in non-abbreviated form, and the inevitable 'Yet Another YAPC report' has also been used.