Here's a recent discovery I'd like to share: you can actually run Greasemonkey scripts in Safari. The solution is simple: install GreaseKit. You can find some good instructions on installing GreaseKit here.
Once installed, you can use any of my Greasemonkey scripts in Safari on a mac just like in Firefox. I'll update the pages for each of my scripts to include this information as well as instructions for installing the scripts in the next few days. Installation should be easy enough though. In fact, you should just be able to click the download link for each file and you'll see an installer prompt. This should also work in Firefox and is a much quicker way to install scripts — another recent discovery of mine, ahem.