Quite self explanatory i guess what classes are there besides the monk that grand Flurry And Improved flurry (not unarmed-monk weapons specified included)
Umm...Whirling Frenzy Barbarians get the same effect as Flurry, with any weapon, while raging. It even works with bows! No later ability to get rid of the -2 to hit, but I think the full BAB more than makes up for that...
Rapid Shot and Improved Rapid Shot (C.Warrior) feats are like flurry with a bow. The latter feat removing the -2 penalty.
Snap Kick feat (Tome of Battle) gives you an extra unarmed attack (only adds half str to damage, all attacks including the "kick" take an extra -2 to hit that round) after your other attacks in melee. The best part is that unlike a true flurry, you can add the kick to ANY attack routine, not just full attacks. You can use it at the end of a charge, with a single attack action, etc...