I wish I could say a Raspberry Pi powered by a mobile phone charger, but like everybody else I'm still waiting.
So, my main computer is the following:
PSU Corsair HX620W
CPU Intel Core 2 Quad Q6600 G0 (with Thermalright Ultra-120)
Motherboard Gigabyte GA-X48-DQ6
Memory 8GB (4x 2GB) Corsair TwinXMS2 DHX PC2-6400
Storage 120GB OCZ Vertex 3; 1TB Samsung SpinPoint F1 HD103UJ; 250GB Seagate 7200.10 (+ 4TB in a Synology DS410 NAS)
Graphics eVGA 9800GTX
Case Antex P182 (which will make for some fun re-running of cables if I do get to swap the PSU) with 5x 120mm fans
Optical Drives LG BH10LS38 BD-RW; LG GH20NS10 DVD-RW