I like themes where the titlebar and the menubar blend together. The only problem I find is that when the window is maximised, the panel tends to mess up the overall feel, because there is too much going on at the top of the screen.
This is meant to be a clean neutral grey theme that looks good even when the window is maximised. In this theme the panel and the titlebar blend together when the window is maximised.
It relies on the clearlooks and pixmap engines.
The metacity is included in the download.