Old English Online: Set up by Jonathan Slocum and Winfred P. Lehmann at the University of Texas at Austin, this site provides a good introduction to the Old English language. Includes lessons, discussion of grammar, and a glossary. The site also contains other classical languages and is worth a look.
Beginners’ Latin: This website is a part of the National Archives in Great Britain. According to the website, this is a beginner’s tutorial for learning the Latin used between the years 1086 to 1733 when official documents were written in this language. Probably the most interesting thing about this is that you do not need any previous experience with Latin to participate. There is also an advanced section as well.