dedicating one of their doodles to him. Not only does it feature the usual Adams paraphernalia (a towel, tea, Eddie the shipboard computer), but it features an interactive copy of the Hitchhiker's Guide to the Galaxy that shows little animations from the Guide when you click on it. Awesome.
UPDATE: If you missed it, Google has archived the doodle at http://www.google.com/doodles/douglas-adams-61st-birthday
You can also check out Really Wild Things, my Hitchhiker's Guide fanfiction. The best part is that it's absolutely free. For now, Really Wild Things is available only in epub format (also here) and PDF format, but I'll be releasing it on other formats very soon. Stay tuned, enjoy, and don't panic.