* What would get you to use KartMe every week?
* What would get you to tell a friend about KartMe today?
What would get me to use it would be something that makes it easier, faster, or cooler than tweeting, blogging, or however else I might let people know about this stuff. (Not that I actually do any of those things while working 12h days at a startup.)
Also: name issues. When I see "Kart" i'm thinking "shopping cart" or "mariokart" -- what's the relationship between that and sharing gadgets or recipes? For me at least, you've got a gap right there. The "K" for "C" substitution also gives me "KMart" associations, which probably isn't want you're going for.
Good luck! Don't give up.
Maybe i should say: "The easiest way to create a shareable list of real world stuff"
Look at posterous -- currently "the dead simple place to post everything. just email us." Pretty wordy, there's really not much else to say about it. But it calls you to action.
Maybe you're "Share anything with your friends and save". Depends on where you want to take it.