I'd add a pair of captive-bred orchid dottybacks. They're lovely, lovely fish and add bright streaks of fuschia to your tanks. They're really like swimming exclamation points in the way that people often claim firefish to be, but they actually swim around instead of just hanging out in the water column.
You should note that some people have reported problems with these fish, but I've never seen any. I still don't know if the problem is that they're misidentifying some other species of aggressive dottyback (translation: purple dottyback) or if they're getting wild, highly unsocialized specimens.
I'm a huge fan of dwarf angels, but choose carefully before adding them to a smaller build. Coral beauty in a 40? Yes. Lemonpeel, flame, or flameback? Maybe. But I wouldn't a multicolour, keyhole, or most of the others in a tank that small. They really do like their territory (and swimming room) and will likely fight with a bonded clown pair over space.
