Yes, i have haggled on various items. too long ago to tell you on what though. but usually on the price of the bike itself, along with a lower price on accessories when buying a new bike. it pays to haggle in the slow season, and when they want to move old inventory out to make room for new stuff.
before i'd haggle at LBS i'd check local pawn shops and thrift stores as well as craig's list. also many LBS's
will have a bike board where locals post bikes and stuff for sale.