I've been trialling some firefox extensions to solve my garbage collection problem.
So far, the best of the lot is the Aging Tabs extension, which I've now got fading out tabs to pitch black if I haven't used them in 5 minutes or so.
PermaTabs was also useful - but there's something about the implementation that irks me. I can't put my finger on it.
Morning Coffee overlaps with PermaTabs; so I haven't really seen it become useful; and the rest have seen little use