For a non-WOTC, 3.0 example: the 5-level prestige class "Tsuruchi's Legion", in AEG's Way of the Samurai (dual-system expansion for the Rokugan setting). It has the ability "blackened sky" -- a full attack with a bow (not a crossbow), for them, uses the Monk UAB progression. That, a +20 BAB, Rapid Shot, and a weapon of Speed makes for 9 attacks in a single round.
Under 3.5 rules, I'd suggest converting that to using Flurry of Blows as a monk of your total character level, but only with a bow.