Here are some interesting Laser Comms DX links I have found. They are listed in no particular order.
Paul Kelley's (N1BUG) Laser DX page is full of interesting information and links.
John Yurek's (K3PGP) Experimenter's
Corner has information and links on Laser Comms. Look down the
page under LASER.
Don Klipstein has some information about Laser pointers, lenses and colour.
Sam Goldwasser's Laser FAQ contains all you would want to know about Lasers.
Tomi Engdahl has information about an Experimental RS-232 Laser Data Link.
GKDesign also has circuits for a RS-232 Laser link.
For DSP try looking at Guide to Digital Signal Processing a FREE and useful online DSP book.
E-mail me with comments, suggestions and corrections.