I've been using winamp for a fair while now, and after my media library corrupted earlier today, I decided I'd use it as a good excuse to try out something new.
I'm particularly fussy about what a media player should do. For starters, a good media library is a must, with good ID3 tagging support. Also, flac support is a necessity, and it can't be too demanding on the resources, as I like to have it running in the background when gaming. Video support is nice, but nothing I'd look for, as I'm pretty happy with VLC for all my video needs. Oh, and one last thing, last.fm integration, while by no means needed, is also pretty neat.
So far I've looked at the following:
Foobar 2000 is pretty good, if you want a REALLY lightweight player. It seems to play pretty much any format I throw at it as well, which is nice. The interface however, is somewhat spartan. It certainly serves it's purpose, but the media library wasn't overly intuitive, and it failed to recognise a lot of the ID3 tags in my library. They do have a new version and website since I last tried it though, so it may be worth a look.
Songbird seems like a good open source alternative to iTunes. It also has a plugin system akin to firefox which is nice. Otherwise, I'm not sure what else to say, as I've barely played with this one.
MediaMonkey - This seems pretty cool, although I've yet to try it. It's another one that seems to follow the itunes format, only this seems to support a massive amount of filetypes. It also supports scripting, which could be interesting to play with. I'm always wary of products with a payware option though, however it does seem that most of the functionality I'd be using is available in the free package.
So, what media players do you use? Which do you find works best with gaming, and are there any that you would totally avoid?

Windows Media Player 11, and well, it works for me and I could care less about anything else in this case. =)

Foobar2000. The newer versions in the 0.9.6.x series are pretty decent. Never had an issue with ID3 tags.
Though I manage my media library through the file system, neatly sorted folders. So I use this program mainly to just play stuff on a large random queue, but have set it up for searching and quick sorting on a few custom settings.

Winamp for me. I sort all my stuff in folders, then just mix and match depending on my mood.
Never tried anything else apart from WMP, which I don't particularly like (I expect I'm just biased because of crappy earlier versions of it).

Media Player Classic Homecinema for video. Winamp for music. I've tried other audio players besides that, since it's grown quite bloated over the years, but I could find no other that could do what I require of it. Namely to exist as a thin strip in muted colors snapped to the top of my screen staying on top of other windows, and to have all the controls on that strip, especially the repeat all/repeat one toggle (notably, I have also been unable to find any skin for Winamp with those features other than the ugly old default Modern skin).

I use Windows Media Player 12. I use VLC for formats it can't play, which isn't all that often (the Windows 7 version of WMP plays all common formats right out of the box).

I wish I could say the same. I have files and folders all over the place, spread across four drives. One day I will finally get around to sorting it all out, but until that day, a decent library is a must for me. I shall have to give the new foobar a blast though, maybe my ID3 tagging issue has been resolved by now

Personally I use VLC since it can play ANYTHING, including mkv and flac. My only complaint is that it is a system hog.

You a right there, that feature in winamp was very useful

Try Columns UI for Foobar. It dramatically improves the interface.
Try Foobar then. It can play anything and isn't a system hog. I use it in the background while playing games just fine.

i think the coolest part of media monkey is the ability to seamlessly send songs to and from an ipod. that said, i use vlc player for all video stuff.

Personally, I'm quite happy with Columns UI. I don't like the more elaborate interfaces, to be honest. Which is why I never really took to WinAmp. But yes, there are many mods for the app that mean you can customise it to your heart's content.

A Codec'd to the max version of Media Player 11 on my HTPC (basically no choice if you want to use the actual media centre app) and VLC / Media Player 11 on my main computer with winamp 5.something for MP3s (not often that I choose laptop speakers over a solid stereo system though)
I have no interest in fancy features, I'm concerned specifically with playing the media I want and nothing else so that combo does me perfectly

I've traditionally used just VLC, but am now looking into Media Player Classic HomeCinema (MPC-HC) for those Matroska (.mkv)-packaged video files. The interface is just that more minimalist.
I must say, though, Windows Media Player 12 has improved quite a lot over past iterations, and now makes a great video player with its minimalist interface. Lack of Matroska support means that I can't view subtitles, though, and when the dialogue is not in English, that causes problems...