ZDoom

Done. Added wildweasel's version.

Here's my take...

Geek before/after:
[img]https://i.imgur.com/qIHmIFT.gif[/img][img]https://i.imgur.com/8LnViCz.gif[/img]
Ubergeek before/after:
[img]https://i.imgur.com/sGiH3JU.gif[/img][img]https://i.imgur.com/TpPKDSL.gif[/img]

These are properly transparent and still in GIF format. Whether due to incorrect settings or some other factor, however, they're a kilobyte larger than the originals.

Giving them a black background was not my intention, as I said earlier.
I got rid of the white outlines, yes, but I don't know how to get rid of the backgrounds/make them transparent, which is why I said someone else might have to do that.

Giving them a black background is pretty much even worse.
These should have the white outlines removed, not have a background added, or it'll look awful in pretty much every theme that doesn't use that exact colour for the background.

The Geek and UberGeek smilies have this tacky white outlines around them, so I fixed them for you

Before
:geek: :ugeek:

After
[img]http://oi67.tinypic.com/6fm83a.jpg[/img] [img]http://oi63.tinypic.com/2ugc5s6.jpg[/img]

You'll probably have to make their backgrounds transparent, I have no idea how to