Flash and Ignite is my standard on Udyr because it will help in some close fights early to just kill your opponent before he can kill you or to kill him if you can't reach him before tower (because Udyr has no gap closing he can just run :D).

It is also very viable to use Ghost for the extra mobility and skill shot dodging but i prefer the Flash for the Flash + Blazing Stampede (stun).

Also very common is Teleport because you need to come back to lane quick if you spam your spells (huge mana costs) and stay up with the farm.