The Piper at The Gates of Dawn.
My friend John Dragonetti first turned me on to this record sometime back in the early 1980s, and it was amazingly fun to listen to back then. And it still is, even though I don't tend to partake of the psychedelic substances so much these days. There is an enduring sense of joyful anarchy in Barrett's lyrics and songs that has stood the test of time. Songs like "Apples and Oranges" and "Bike" will always be up there near the top of my list.
There are obits all over the web right now, but there is a lot of good info on Syd over here at Wikipedia.
Syd eventually withdrew from the band due to mental problems, most likely brought about from his use of psychedelic drugs. I found it ironic that on the same day his death was announced, the Los Angeles Times is running this story on the potential for psilocybin (from hallucinogenic mushrooms) to be used to help addicts and people with terminal cancer attain feelings of spiritual transcendence. I have no doubts that this is possible, but as demonstrated by Syd, too much of a good thing might not be so good. The story mentions that subjects in the trial who took psilocybin were only given a one time dose, and many reported that the experience was "among the five most profound events in their lives, rivaling the birth of a child." I'd be interested to see studies on the different experiences of medicinal psilocybin users vs recreational psilocybin users.
The Times article concludes on a funny/scary note:
"David E. Nichols, a Purdue University chemist who synthesized psilocybin for use in the study, said the effects of psilocybin could vary greatly, depending on the mood of the user, and could be dangerous.
"If you take psilocybin and go watch 'Friday the 13th,' I can guarantee you won't have a mystical experience," he said."