In the Q&A moot asked for better versions of the current banners, and in the new banner contest sticky it came up again: >>649210 A spinoff thread for this was requested in there. Now that it's banner season, let's finish it.

Here's an archive with new versions and duplicates removed (v5):
http://www.mediafire.com/?ev935dtjd6v78i2

The spongebob one is missing from the official rotation. Why, and what are we going to do about it?

The Simpsons one had really bad image quality. There's a bunch of new versions, so pick one or make more.

Code Geass and Garfield have image quality problems. Got any clean source images?