The writers for Disney's Atlantis, Klingon from Star trek, etc. All created languages during the course of their creations, and most of them are available on this site, called Omniglot. At the bottom of some Omniglot pages there are fictional fonts that you can use for writing that should fit what you're looking for. Personally my favorite is the Daedric alphabet from The Elder Scrolls games, but there are a lot of languages and fonts to browse on this site.
For a nice overview of fonts available from Omniglot, see its fonts page.
Dieter is a website made by Dieter Steffmann that hosts a wide variety of fonts. While I personally don't feel that it has a lot of fantasy fonts similar to Omniglot, its selection of fonts covers a wide variety of text types and is worthy of mentioning as well.
Thanks to @Storyteller for the suggestion.