Blackle Mori's online drumkit databender. Play around with the settings until you come up with a sample or pattern that you like and play it. Works a little bit like a tracker in that you can build pretty complex patterns - not just drum lines, probably entire songs.
An open-source drum machine and MIDI sequencer that also uses AI technology to figure out melodies for the patterns you program.
An archive of recordings from the early days of phone phreaking- stuff like conversations recorded off of bridges, tone sequences, war stories, stuff like that.
An archive of recorded messages and error tones from United States telephony networks. Available for online listening or free download.
The Philharmonia Orchestra has released samples from several dozen instuments under a Creative Commons license (CC-BY-SA). Commercial works which use these samples are explicitly approved.
ODO has made available several hundred megabytes of Commodore-64 samples, stright from the SID chip.
Mozilla's open source speech recognition project. They're asking people to contribute samples of themselves speaking sentences on the screen to grow their corpus.
3712 links, including 188 private