Yeah this is close(ish) to having the genius sidebar, thanks iBrarian
You can also get this within your playlists (I use a lot of playlists)
If you click on the "View" button in the top right above your playlist
And set view to "Artist List"
This will allow you to view a list of all the artists with tracks in your playlist
You can then click the "In the Store" tab to see the recommendations for that artist, not bad
Try doing this in your "Recently Added" playlist to get recommendations for stuff you've just bought
Apple have made iTunes incredibly convoluted now
They made a ton of money out of me from the Genius sidebar - just scanning my library and buying heaps of recomended songs - IT WAS SO SIMPLE!!!!