I use eMusic to satisfy my insatiable desire for music. It's great. However, you have to download each track individually: there's no way to get a whole album at once (at the moment). In Firefox, I found I could only download two tracks at a time; this meant it took quite a long time to download 10 tracks, say, as I could only have two downloads going at once.
I always thought this was down to eMusic, but it occurred to me today that it's probably a Firefox setting. Lo and behold, it is a Firefox setting. If you want to fix your browser to allow more than two simultaneous downloads over HTTP, do the following:
I can now have 10 or so downloads running concurrently (the first typically finishes before I've got round to starting number 11!). Much better. This might even speed up standard web browsing, as you can download far more files from a single server at the same time. (Though I don't know whether setting it too high might make it look like you're trying to launch a denial-of-service attack or something.)
To further improve your download experience, I recommend the Download Statusbar for Firefox. Peachy.