What is an IDN (internationalized domain name)?

There are no restrictions from ICANN on owning an accented letter domain name in .com [or.net]. In 2000, all the 170+ accented letters such as é,ó,ç,î,ž
became available for registration.
In some foreign countries those actually use these accented letters, there is a key right on the keyboard for it, and can be typed just like any other letter. All of these accented letters have a special code known as "punycode", which allow your web-browser to distinguish the accented letter from the regular letter. All 170+ single
accented letter domains are now registered.

See here list of IDN for sale
http://www.afternic.com/namesbyc.php?c=230&