What can I do with Scrap Metals?

Craft it into Reclaimed.

combine scraps into ref and get enough ref to trade for a key?

give them to me ;)

Crafting
3 Scrap Metal makes 1 Reclaimed Metal
3 Reclaimed Metal makes 1 Refined Metal
6 Refined Metal can be traded for a key in some places, if I remember correctly.

You can now start crafting HATS!
http://wiki.teamfortress.com/wiki/Crafting

dammit. i entered this topic hoping for real scrap metals. :(

and yeah, I used to just acquire a shitload of refined metal and throw it up onto TF2 Warehouse to exchange for other things I wanted -- been over a year since I've done that though, so no idea if that's even a viable option anymore