Awhile ago, I remember using a site that would give you a mobile phone number to use and then notify you by email so that you could confirm it, or something like that (that way, you don't have to give out your own all the time). I don't remember exactly how it worked, but I remember there being a few of these sites. Does anyone know the names of any of these sites? I tried searching. Couldn't find anything.

Oh, sorry, my post wasn't entirely clear (I'm kind of tired). This is basically so that you can register for sites that require you to give out your mobile phone number.