1) A function that can hide the ROMs you've already downloaded. 2) Make the actual downloader minimizable 3) A mass-rename function for archives to include both the region, and the release group
A better search engine would be nice too. When I have to look for a particular ROM, I need to go to the RomUlation website...
Not from my experiences: For some things, you have to type in the whole name (forgot which games, but I'll remember later, I hope...), also regions can be a real pain in the ass with the downloader.