Where does Winamp save playlists (that I don't manually save)?
 

Can you tell me where Winamp saves the playlists I create? It remembers them, but I can't find where it puts them. I'm not talking about manually saved playlists. I want to back them up using automated backup software, since I don't like having to manually save a playlist every time I tweak it. What format are they stored in?

Media Library > Playlists are the .m3u files in the Winamp\Plugins\ml folder.
Note, you also need to backup the corresponding .vmd files in the same folder,
as referenced in Winamp\Plugins\gen_ml.ini (which also needs backing up), eg.

query14_name=Main Playlist
query14_val=plf60AF.m3u
query14_mode=32
query14_meta=metEFAF.vmd

From the FAQ

Backing-up Media Library database ratings/playcounts, playlists, etc:
http://forums.winamp.com/showthread.php?threadid=158332
http://forums.winamp.com/showthread.php?threadid=182413
http://forums.winamp.com/showthread.php?threadid=221054

winamp.ini, studio.xnf, gen_ml.ini, reg entries, backups etc
http://forums.winamp.com/showthread.php?threadid=158332
http://forums.winamp.com/showthread.php?threadid=209601

My question seems like the same question, but I'm not sure. I'll explain in more detail. I want to know WHERE Winamp (using v5.24) stores the playlist that comes up when it STARTS (the current one when last shutdown). I don't see any m3u files at all in the plugins\ml (or any)subdir. I originally hoped it might be in an .ini file somewhere but don't see anything in any that I've found. My next hope was the recent.dat file, but that has WAY more than what my last playlist held.

The other (and corresponding) part of this question is that when I have accidentally cropped a playlist is there any way to "undo" the action? Or to get the list wherever it is stored before it is overwritten somehow (I assume the same location as above when first opening?).

I have had my machine crash and then Winamp comes back up with an "old" playlist, which leads me to believe it writes the "current" one out somewhere when it exits properly???

Hope this is clear enough. Any help on this is greatly appreciated, its been bugging me for awhile.

winamp.m3u in the main Winamp directory.

You can try DrO's Playlist Undo for that.