I was just thinking that the AoE from his torch and the slow from his harpoon and the movement speed boost/shield would kinda make Rumble a pretty good jungler, but nothing like Skarner/Lee Sin. Has anyone done it?
As long as you can land your harpoons, jungle Rumble is actually really good. Running tanky AP runes (I run flat AP Quints, MPen reds, flat armor yellows, and either scaling MR or flat AP blues) and a combination of masteries that gives you MPen and armor (I run 21-9-0, picking up Bladed Armor, rather than Veteran Scars).
As for starting items, I tend to start either boots + 3 pots or an Amp tome to get an earlier revolver.
Found a link to a replay of CLG's Saintvicious! http://www.own3d.tv/video/285384/Saintvicious_Jungle_Rumble_Post_Mastery_Change...._It_is_pretty_damn_strong
Jungle Rumble is out shined by so many others, its not even worth it. Without a strong leash you will have to back after doing the blue buff. Do to rumbles lack of sustain you get so low in the jungle your first few run throughs it is easy to counter jungle. Even with spell vamp it only applies 33% on your Flamespitter (
Do it for fun? Sure.
Do it because its good? No way.