It's so simple I can't believe no one has done such a thing...
I don't have the time to learn the Winamp plug-in interface, or I would have written it myself till now...
Here's the idea:
I want a plugin that would run a specified program when a file of some special type (extension, understand) occurs in the playlist. For example when a txt file appears, it would open it in notepad.exe or when an image comes, it would run c:\whatever\imageviewer.exe to view it. The user should simply specify which extensions to which programs are associated. There's no need even for a special interface for that - it could be made by editing an ini file in the plugins directory, which would look like that:
txt,tab = notepad.exe
jpg, gif, tiff = c:\whatever\imageviewer.exe
So one would be able to make playlists with the cover and he lyrics of the album and there would be no need for special plugins to view them.
If anyone likes the idea and makes the plug-in, please send me a notification by e-mail to firstname.lastname@example.org.