How has it worked for you? I'm getting a new host and it has it. I know discussion board software typically incorporates GZip compression, but they wouldn't list it as a WWW account feature if it were just some silly utility forums use, I think.

Have you used it for any other purpose? How does it work on the technical side, performance, speed, compatibility etc? The advantages and disadvantages?

It's nice if you get visitors on dial-up, but otherwise there's no point. It may also help if you have a very limited data transfer bandwidth.

That has me interested. I actually have a quiz on my site and a big one. Last time it was almost 100KB in one script (javascript, client side). Would gzip make it faster for people with dial up or slower? Perhaps faster if in client side javascript, but wouldn't on the fly zip/unzip slow down the PHP version?

It would increase the speed of the PHP version, at least it should. Probably would increase the javascript as well since it would transfer to your visitors' machines faster, but I've never used it on javascript.