The University of Liskom has a very extensive department of languages. You may be interested in learning Darunian, but you might also like these:
Verdurian (Verdurianu) This is an amazingly complete language. It's got a complete grammar, a thematic dictionary, lessons, everything--even ten other languages. There's even a message board where you can post in Verdurian and other Almean languages. Click here if you'd like to hear mp3 files of what they sound like. There's also an interesting culture that goes with each of these languages.
(If you're curious, the text above says, "Dhitelán mu cum pén veadhen er mësan so sannam," or "Go in peace to love and serve the Lord.")
David J. Peterson's Web Thing (Cosa de Internet de Davidu Y. Peteri) Apparently this person is well known in the community of language makers. He has created 12 languages and has written some notes on language in general. (The banner above says, "Fight Linguistic Extinction: Invent a Language!" in Kamakawi, one of Sru. Peteri's languages. Click on the banner to get your own similar banner!)
Also take a look at a very interesting constructed language, Toki Pona, which was created by Sonja Elen Kisa, a male-to-female transsexual. It's only got 120 words and has a very simple grammar; I was able to learn it in less than a month. While it's supposed to make people think in more simple terms, I see it as the best candidate yet for an international auxiliary language. I've made my own Toki Pona page.
All about Láadan (click to see my Láadan page)
If you're interested in gender issues, you may like Láadan, which, according to its creator, was designed to suit the needs of women:
I can go on to tell you that I saw two major problems -- for women -- with English and its close linguistic relatives. (1) Those languages lacked vocabulary for many things that are extremely important to women, making it cumbersome and inconvenient to talk about them. (2) They lacked ways to express emotional information conveniently, so that -- especially in English -- much of that information had to be carried by body language and was almost entirely missing from written language. This characteristic (which makes English so well suited for business) left women vulnerable to hostile language followed by the ancient "But all I said was...." excuse; and it restricted women to the largely useless "It wasn't what you said, it was the way you said it!" defense against such hostility. In constructing Láadan, I focused on giving it features intended to repair those two deficiencies.
Even though I disagree with the idea that language can actually change thought (some languages have the same word for all colors other than black and white, but experiments have proven that their speakers think of red, yellow, blue, and green as different colors just like we do), I like the concept of Laadan. I find some of its words very useful. If you'd like Láadan lessons, click here.
Another language that has some useful features in common with Láadan is Ithkuil. If you like the idea of a logical language, try Lojban. It is said that Lojban copied a few grammatical features from Láadan.
Kaupelanese (same name in Darunian) A Pacific island language for a very interesting Pacific island culture. Makuwa Airlines will take you to Purikali if you go to Liskom International Airport.
Itlani.org The author of this site can say just about anything in the Itlani language. The culture is interesting too.
Languages of Bergonia (Lingua de Bergonia) The really interesting part is the culture.
Alurhsa Home Page (Pajina Casa de Aluria) In a format similar to Itlani.org, this site showcases the Alurhsa culture.
If you're interested in artificial languages, you might want to try The Language Construction Kit and How to Create A Language. The Zompist Bulletin Board and the Conlanger.com Bulletin Board are also very helpful, as they can put you in touch with other people who share your hobby.