[if you're allergic to reading mildly rambling text, just skip to the nice screenshot at the bottom]
i don't know about y'all out there, but one of the killer features for me in amarok when i first started using it was the "append suggested songs" feature. i do love last.fm radios, but the idea of having amarok play me songs that i already have but just maybe never saw the connection between, all automagically, seemed like a brilliant concept.
however as anyone who had taken a peek at the 1.x code for dynamic mode knows, it was not the most elegant of features. it wasn't the most cleanly designed piece of code either. and so, things being as they are, it was tossed by the wayside when 2.0 came around for the new nifty Dynamic Playlists that we have.
i would wager that a sizable chunk of amarok 2 users have no idea what Dynamic Playlists are. what do they do? why do I have so many pretty sliders? what does it mean when I ask amarok for 100% ska and 100% britney spears and it spits out a playlist with neither ska nor britney? putting aside the fact that by denying me of britney spears it has already significantly degraded my quality of life, i've always found Dynamic Playlists hard to use because put simply, I don't have the metadata to make them useful. I don't have my tags labeled, nor do i have good genre tags, or even any good ratings (side-effect of amarok development, my database never lasts more than a few weeks). so i can't tell dynamic playlists what to play me.....
....but no longer! i've finally scratched the itch that i've had for months and months, and resurrected a similar artists feature like you had in 1.x. but as a testament to the new Dynamic Playlists, this is really two things:
1) Much more powerful than the suggested songs in 1.x
2) Just the beginning
3) The best vector for delivering britney spears music to your ears
I have a sneaking suspicion that one of the above is wrong, but can't quite pin down which. in any case, without further ado, this is what it looks like:
this new type of custom bias queries last.fm for artists similar to the currently playing track, and returns any that you have in your local collection. so you can play music you never knew you had!

but more than just creating a new bias, we now have a framework for any component to register its own new bias type. so a new service, say magnatune, could add a new bias that lets you also filter on magnatune tracks, or do a bunch of other nifty things that would otherwise not be possible. someone could easily write a new bias type that favors artists that will be playing shows nearby! this is all to say, expect great things. because even though you can't always get your britney spears, amarok is still here to comfort you.