My favorite tool is ANTLR. It implements lexers, parsers and tree parsers via the same conceptual framework: LL(k) analysis. The generated code is designed to be very close to what you would write by hand, which makes it straightforward to debug and understand. ANTLR is a tool for programmers by programmers, with an emphasis not on theory but on problem solving.

My main contributions have been some source code, including an ANSI C and GCC C translation framework including lexer, parser, tree parser, and tree emitter. The GCC Translation Toolkit goes from preprocessed source to tree and back to source and makes it easier to get to the fun part -- the actual translations.

I'm also the primary answerer of questions on the antlr-interest list, which is currently the main forum for ANTLR questions. I have a lot of fun solving those types of problems.

Also, thanks to Bram for pointing out BitTorrent for movie distribution. If I understand correctly, it seems BitTorrent is best suited to a "release" instead of occasional downloading, but I'll still make sure it's one of the primary options for getting it.