I'd like to see some more font options. The stock web fonts tend to look a little stale because we see them in so many places.
It would also make things slightly easier if there was a download button next to the web address--this might be tricky to implement but it would save users several seconds.
Yes, I should definitely add more fonts, it's useful. But does anyone know if embedding open sources fonts is fully legal? And what about commercial fonts, i.e: Arial, Comic sans MS, etc.? It is quite difficult to understand the licences for my usage.
For the download button: yes, I know it would be nice, I thought about it, but decided to delay its implementation, because as you say, it will certainly be tricky to make :-D It will come!
If you stick to free or standard fonts, I think the worst that happens is that you have to take them down, especially since you're not charging for use.
And whatever you do, don't use comic sans (http://bancomicsans.com/home.html).