Is there a way to convert a website to a mobile version? There's a forum I like to visit, but it's not as convenient as this one. The gamesas mobile version is very nice.

I believe the website has to create a mobile version of their site.

Short of writing your own CSS and using a mobile browser that supports custom CSS, no, there isn't. Opera Mobile and Firefox Mobile (with Stylish addon) are the only ways to do this that I know of.

The closest alternative is Opera's "Single Column View" Which for many sites is actually pretty decent.