A .tel domain name, like a virtual business card, is primarily for people / businesses who don’t have a dedicated website but need simple mechanism to put all their contact information on the web.
So if your name is Raghav, you can register a domain like www.raghav.tel and put your phone numbers, email addresses, IM ids, snail mail address, links to social networks, etc – all in one place.
How is .tel Different from .com
The main difference between a regular .com and .tel domain is that the latter stores all your different contact information at the DNS level (like whois database records) and you don’t have to worry about creating a website.
If you are willing to book a .tel domain for your own self (see example), just head over to Domain Monster as they are now accepting pre-orders. You can even try a .tel domain before buying one using this link.
Personally, I can’t think of a single reason why would someone invest in a .tel domain where there so many other services offering similar features for free*.
*The pre-order price for domain amit.tel is around $400 with a three year registration. Simply not worth it.