Jeremy Steele has just released the alpha version of an .htaccess generator tool. While it's not yet complete, it is still useful, so I thought I'd pass it along. Even if I only ever use it to quickly generate www/non-www redirects, it's worth bookmarking. He's going to be adding help files and other goodies in the future, but there's no reason not to use it as is now. I've got it bookmarked for future use.
Of course, be careful with .htaccess files. Make sure you don't overwrite an existing file, and double-check everything so that you don't accidentally block the search engine bots or something equally horrendous.