Seems like a cool idea.

However, I'd recommend doing some more brainstorming on the name (provided this is the brand you've settled on, and not just the dev site).

I know all too well that it's tough to find a good domain these days...but I think you can do better. I find that the average user's mind will have a hard time following ONE changed spelling convention. And you have two (the double-m & the double-p.)

Jummp.in? Cool. Jumpp.in? Sure. Jummpp.in? A little too cumbersome to explain to my friends when we're hanging out (& have any chance of them remembering it).