I thought I'd spend a few lines in irb and implement two.io for you right here in a comment ;-) Here are the available two letter io names from /usr/share/dict/words, /usr/bin commands, and bash builtins:<p>ah.io, ay.io, di.io, ea.io, ey.io, fa.io, fc.io, fe.io, fg.io, ha.io, he.io, ju.io, ka.io, oe.io, or.io, ow.io, pu.io, ra.io, te.io, ti.io, tu.io, ut.io, wa.io, wi.io, wu.io, wy.io, ya.io, ym.io, yn.io, yr.io, du.io, ld.io, lp.io, m4.io, nm.io, wc.io<p>UPDATE: It just struck me that two letter domains might be rather hard to register. I'm looking at the T&Cs now. It is notable how many <i>are</i> marked as being registered in the WHOIS though.<p>UPDATE 2: Neither of the third party registrars I tried allowed two letter .io domains but the central nic.io does.<p>UPDATE 3: I visited rb.io (which I wanted ;-)) and found this blog post of just a cpl weeks ago on the same topic: <a href="http://www.russellbeattie.com/blog/two-letter-io-domains-available" rel="nofollow">http://www.russellbeattie.com/blog/two-letter-io-domains-ava...</a>