I use a very low-tech solution: I stick a <pre> tag at the start of javadoc comments, and make liberal use of empty lines for spacing.

So I don't use any advanced html tags and stuff. Of course I use @link, which is the most useful feature of javadoc.

BTW, maybe the 'meaning' of <style> tags should be clarified for ambitious documenters... It seems they only affect the one javadoc they are inside of, which is pretty useless.