Udyr can be strong farmer, between phoenix and turtle, he's quite difficult to push out, as long as he knows his enemies. He's in a poor position to get fb's though, lacking a ranged poke/nuke (not counting phoenix fire)...personally, I prefer to jungle with him. Just a personal preference, even if it means I need to take rally over flash (exhaust is just too good at locking down people to forgo for flash, since they both have equal cooldowns now (I think both are 210)), I still find myself rolling if I don't get my jungling managed (wards and them taking their buffs at 4 or something).
I think there's a handful of quite viable solomid melee; singed (for his big hp stack and poison's awesome creeping ability), cho (his hp back on minion kill makes for epic lulz. I've gone mid against moderate sivirs, and just dodged their boomerang and killed minions while they wailed on me), udyr (reasons above), possibly pantheon (he has a low mana cost ranged poke/last hit tool, he has some CC, and a nice passive for escape/survival). The reason it's rarely seen though is that in general, the ranged carry is preferable. Your sivir can camp the lane and not steal last hits from people and can visit a lane to knock towers, the tf is a gank machine, karthus is a demon if he can get his lay waste off at the right time, teemo is nigh ungankable after 6, thanks to shrooms (and is very difficult to bully), even ashe can farm up some dps, then proceed to launch the longest stun in the game + a nuke at any lane once a minute. And all these examples give terrific map control, let alone gank potential.