I've read The Hitchhiker's Guide to the Galaxy more than once over the years, and it still makes me laugh.
There's just something about Douglas Adams' style. One minute it's completely ridiculous, the next minute you're thikking, "You know... that actually makes sense."
Marvin has to be one of the best characters ever written, and "Don't Panic" is probably the most famous piece of advice in science fiction.
Some books get old after a while. This one never has for me.
Wayfarer