gTLD Guide

All gTLDs/sTLDs

.aero STLD the air transport industry.
.asia STLD companies. organisations and individuals in the Asia-Pacific region
.biz GTLD business use
.cat RTLD Catalan language/culture
.com GTLD commercial organizations, but unrestricted
.coop STLD cooperatives
.edu RTLD post-secondary educational establishments
.gov RTLD government entities within the United States at the federal, state, and local levels
.info GTLD informational sites, but unrestricted
.int RTLD international organizations established by treaty
.jobs STLD employment-related sites
.mil RTLD the U.S. military
.mobi STLD sites catering to mobile devices
.museum RTLD museums
.name GTLD families and individuals
.net GTLD originally for network infrastructures, now unrestricted
.org GTLD originally for organizations not clearly falling within the other gTLDs, now unrestricted
.pro GTLD all professionals and registered companies
.tel STLD services involving connections between the telephone network and the Internet
.travel STLD travel agents, airlines, hoteliers, tourism bureaus, etc.

The ones in bold are great investment vehicles currently in my opinion.