This topic's been revived! Yay! I've been stalking this topic for like three months now.
So, flying Twinborns... Steel Compounders. Wear a wing suit (think flying squirrel), push off an anchor, and compound speed. It's not really flying, though, just falling with style. Also, it really depends on the nature of speed. Does tapping speed increase the rate your body moves, like going, say, five miles an hour while your body is doing the work of walking two miles an hour, or does it just make you move faster period?
Something that's come up a while are Duralumin Ferrings. Duralumin increases your connection with other people, creating strong bonds in moments. However, some say that this connection is two-way; you also feel the effect of Duralumin. I don't think that's really the case. We have WoB that Feruchemy protects you from the adverse effects of tapping or storing, so Brass Compounders don't burn themselves for example. So, why should Connectors be any different?
From the Q&A, I think anything about Identity is going to be a RAFO, so there may be something amazingly awesome about storing Identity we don't know yet... hm...
An Iron Compounder in a second-trilogy Scadrial could basically be Spiderman. By making yourself incredibly light, a lot more things become anchors. And, assuming we get giant metal frame skyscrapers to Pull-kour on, we get a team of your friendly neighborhood Twinborns. I smell fanfiction.