What's with the "x" in "Hunter x Hunter" (and other anime/manga)?
I've done some searching about the names like this, and I wasn't able to find any particular explanation. Some people say it's just for style, other argue that the × is another form of "vs" (which kind of makes some sense), or "and" (like &amp;), or "with". (Not to mention that it might also mean "kisses" like in "xoxo" = "hugs and kisses", but that's most likely irrelevant :P)

It's worth noting that it is not uncommon to find odd letters in anime/manga titles (e.g. Lucky ☆ Star - らき☆すた has a star in the name) and even in character names (e.g. Black☆Star from Soul Eater has a star in his name as well). Also the 'x' in "Hunter × Hunter" is not actually the letter 'x', but rather the symbol ×.

So, considering the above, I would personally say that it's just for style.