Same one as in "madman", obviously inspired by MEXP for Winamp. IMHO it's the most functional UI for a jukebox player. And don't tell me please to use madman instead, as it may be functional and stable, but does not support virtual playlists, as AmaroK does.
Also, an option for auto removing the played track from the virtual playlist would be nice.

use madman instead Different apps have their own UI, deal with it!
I love Amaroks UI btw =)

You can't tell someone to make their program like another one and except not to be told to use that instead. Just looking at the screen shots, it appears to be one of those annoying jukebox players that assumes all your id3 tags are 100% perfect and consistent. There isn't much point in writing a program similar to one already out there.

What would be reasonable would be to suggest virtual playlists for madman. Or if there's some specific feature of madman you miss in amaroK, it might be ok to suggest it.