The only thing I used the 3G in my Kindle for was when I was in Egypt. Rather than hunt down a wifi signal for our netbook, I could check my gmail and post to twitter from my Kindle. I was on a train between Cairo and Luxor and posting to Twitter about how I'm on a train in BFE. I was telling friends about camping in the white desert from my Kindle.

Completely free of charge, in the middle of the Egyptian desert. That was definitely worth it.

If you don't travel so much, save $50 and get the wifi-only version.

It saves me quite a bit of money.

I never buy books until I'm sure I want to read them. When I first got my kindle, I bought more than one book at once, and I regretted it.

Now I keep a backlog of sample books on my kindle. When I finish my current book, I can pick something from the many sample books I have, and if I like what i read, I buy it right then.

Of course, I tend to carry my kindle quite a bit out and about when killing time (auto shop, kids swim lessons, etc)

Only the convenience factor, which could be a good reason, but I wouldn't call it killer. 3G is still easier to find than free wifi.

That said, I'm using the original Kindle 2 (uses Sprint's network) in Norway, so effectively I have no wireless option at all, and I've survived just fine.

Damn. I may have just talked myself out of the 3G version.