The Acroplane comps have introduced me to some fantastic new stuff.
That said, comp CDs are an often abused form of self-promotion for the compiler, and Belfast & NI have about a million compilation CDs from various orgs and outlets that don't do much for anyone. (edit: the compilations that is, not the orgs & outlets)
I think compilations as carefully-composed mixtapes, crafted with specific songs, moods, themes and compatibilities in mind, rather than a cynical trawl of whatever artists are currently 'in' would be great.
I tend to agree with you there...Especially when it comes to compilation from organisations in Ireland its not always about the Artists! there are sooo many (that im probly not allowed to name) NIMIC, BLAST:BEAT, SONI...the list goes on
Ive been surfing the web and it seems that in Eastern and Centeral Europe The Humble compilation is a Haven for unsigned bands and still regarded as an achievement for all genres
The Silent Ballet put out amazing compilations of instrumental music pretty often (stifle that yawn, it's not ALL postrock, there are lots of other genres that don't use vocals much) - they're a great way to find new bands that would otherwise not get much exposure. Yes it's a bit "Fans Only" but they're surprisingly popular.
But really, in this age of Spotify playlists and last.fm radio, compilations seem to have lost relevance unless they are quite niche.