I purchased my first .mobi domains just now. It was a little more expensive as the “land rush” is currently operating.
I was only going to buy 1, then I thought of another one worth buying and with a bit of luck it was still available.
If I get one of them, the dot com equivalent probably has a four figure value.
There are probably people out there who don’t think mobi will be anything, but I am fairly sure they are the same people that said the same thing about .info, .biz. Mobi was for a definited purpose, unlike the non .com .edu and .org extensions.
Some mobi domains are already on sale for five figure sums.
Read all about the mobi domain land rush here. If there is a .com domain you always wanted to own, go and check if the .mobi is available.
One thing I should add, when you are thinking of a domain think if the site would be appropriate for a small screen. Entertainment, games and travel are all possibly good niches.