Yesterday, the City Council of Tacoma (the third-largest city in Washington) repealed its stun gun ban; thanks to Stephen Stamboulieh and Phil Watson of the Firearms Policy Coalition. In recent years, stun gun bans have also been invalidated or repealed in Michigan; New Jersey; Wisconsin; the District of Columbia; the Virgin Islands; New Orleans; Overland Park (the second-largest city in Kansas); and Annapolis, Baltimore, Anne Arundel County, Baltimore County, Harford County and Howard County (all in Maryland).
Stun gun bans remain in effect, to my knowledge, in Hawaii, Massachusetts, New York, Rhode Island, Philadelphia, Wilmington (the largest city in Delaware) and smaller towns. The Massachusetts and New York laws are being challenged in court. Stun guns are also heavily regulated (e.g., with total bans on carrying in most places outside the home) in some other places. For more, see this article, though the listing of restrictions in Appendix II is now out-of-date.
Disclosure: I’ve consulted a very little bit, through the Firearms Policy Coalition, on some of the stun gun litigation, and I’m also involved pro bono in some such litigation through the Center for Individual Rights.