If I remember, one of the entries for the 4th Obfuscated Perl contest was a befunge interpreter written in Perl... (but I can't check because it looks like the site is unavailable at either itknowledge.com or tpj.com: does anyone know if this is cache'd/archived anywhere?)

And a quick search on the internet finds a Befunge interpreter in Perl...

I got seriously obsessed with this Befunge and other similar languages (stack based, 2-dimensional languages, possibly with multiple Instruction Pointers - e.g. threads).
To the point of having to throw away pages of notes because I couldn't get to sleep at night for thinking about call stacks and how to implement Object Orientation in my prototype language...

Cheerio!
Osfameron