There is a wealth of information about constructed languages on the Internet. The following list is just the tip of the iceberg, but I hope you enjoy looking up some of these sites.
Xaramblings is a new site by Amber, which is written in Xara and is well worth visiting.
Richard Kennway's Constructed language list is an excellent starting point with which to find information on many constructed languages.
Paul Bartlett's site has good concise information with many useful links.
Don Bhaheta also has a webpage containing useful links to many constructed language and linguistic sites.
The Langmaker site run by Jeffrey Henning is full of resources and information about many constructed languages, as well as interesting articles.
The Babel Text site, also run by Jeffrey Henning contains samples of the same text translated into different constructed languages.
A similar site is The North Wind and the Sun, compiled by Jonathan North Washington. It contains translations of the same text in different dialects and conlangs, many with audio samples.
Amber's site contains detailed information on the constructed language Cenlatorre, as well as Karath and Nyo'fa.
André Steffens, The Gray Wizard, Pablo Flores, Natalia Gruscha, Jonathan North Washington and Muke Tever all have sites dedicated to the languages they have constructed and are well worth a visit.
Finally, to see another example of a site in a constructed language, visit Volapop, which is written entirely in Volapük.