It started with del.icio.us/ (which now ironically redirects to http://delicious.com), and now it’s becoming more the trend to create a domain name with the extension included for effect.
With unique .com domains harder to come by, and dropping vowels like flickr.com so last generation, some countries must be trying to cash in on the success such as Tuvalu which has something like 10% of GDP from domain name sales of .tv.
Some recent names I’ve noticed are http://identi.ca, http://chi.mp and http://cyclo.ps.
I have even considered some recent projects using this new trend, but the combination of either the 2 letter extension not existing (For example .ld) or it’s not possible to get domains from a registrar (For example .er) it will take some time.