Here’s a short tip: If Amarok 2.0 doesn’t add any songs to your playlist or collection, or the collection scan is getting hung at up 47% or 79% try installing mysql. Since Amarok 2 now makes use of mysql as its backend, it expects mysql to be installed(nope, mysql-client won’t do either). As a result, after scanning, it cannot add the songs to the collection database and the process just stops.
Just install mysql, and you should be rocking to music on Amarok again