An icon of 1960's counter-culture, the Haight remains vibrant via a concoction of great clothes, assorted and lively street-folk, and some of the hottest hippie girls human eyes have seen.
Haight clothing shops offer some of SF's most exciting wearables - primarily in vintage wear (primarily, Wasteland & Held Over) and furry play clothes (see Burning Man) at Piedmont, with a number of high quality new-clothing boutiques sprinkled about.
The Red Vic Movie House runs a full calendar of classic and independent films, and often hosts a lively audience.
The neighborhood adjoins the Lower Haight, Buena Vista Park, the Golden Gate park, and its Panhandle. Famous/former residents include the Grateful Dead (710 Ashbury), Janis Joplin (112 Lyon) and Charles Manson (636 Cole).
For those fiending some smokable delight, the intersection of Haight and Stanyan is a popular marketplace. Remember, it is not legal to buy or smoke marijuana in San Francisco even though it sometimes appears otherwise.
Otherwise, feel free to dig deeper into the neighborhood with local robot engineer, John Camp :)
Wikipedia: http://en.wikipedia.org/wiki/Haight-Ashbury,_San_Francisco,_California