Ok being as I don't have anything particularlly super fabulous now I'll post my favorite one.
Acropora Microphthalma, not rare, not stunning colored, but it does grow like crazy, it can take a beating and keep on ticking

Actually I'm just waiting for everything I have to kind of fill in over the next few years then we'll see what stings what and restrticts who's growth.
The great thing about this piece is that I had a "colony" about half the size of this, however I whacked it and literally gave it a flattop, right to the base, so it encrusted and eventually branched out as viewed above, now I
glued this to another rock piece, and wouldn't you know it I whacked that piece as well as it grew out, it has encrusted as well. I also found another color morph of the microphthalma and mounted it "horizontally" (it's flat against the rock but the rock is at about a 60 degree slope) but it's making a nice base before shooting up any stalks.
What happened to the frag of this I whacked off? Well I didn't want nothing my micropthalma growing in my tank so I just glued it to the in the back... oh yah it's encrusting there too!