ICANN is now accepting applications for new generic Top-Level Domains (gTLDs), which could quickly increase in number from the mere two-dozen or so existing gTLDs which presently include .com, .net, .org, and .biz.

Just a few years ago, it may have seemed that the domains “to the right of the dot” would, or should, be somewhat limited in scope, perhaps to a handful of broad categories, such as the educational (.edu), governmental (.gov), or commercial sectors (.com). Indeed, previous policy on the expansion of gTLDs has been relatively conservative, with slow but steady additions, including more recent additions .mobi (mobile communications) and .xxx (adult content), among others. Now, just about any established corporation, organization, or institution in good standing may propose and apply for a new gTLD.
It should be interesting to see which types of entities seek to apply and how many applications will emerge. Two factors which might limit the overall numbers are the sizable application fees and the logistical considerations.  For example, a US$185,000 evaluation fee could present a substantial barrier to some. Moreover, the proposed program requires the operation of a domain registry and a demonstration of technical and financial capacity for such operations, including the management of registrar relationships.
In early May 2012, approximately two weeks after the new gTLD application window closes, ICANN will publish a list of the applications. The deadline to register in the TLD Application System is March 29, 2012.  If timely registered, it will be possible to apply until the April 12, 2012 application deadline.
Several stages of the application process will follow the initial application period. For instance, there will be a comment period for submitting comments for consideration by the evaluation panels. There will also be an objection period for submitting formal objections.
The first set of new generic Top-Level Domains is not expected to be operational until sometime in early 2013.