Ooh I do like a corset belt. So does Posh Spice, though I suspect hers doesn't strain against extra pounds gleaned by consuming one too many bottles of vino.
This vintage one, £35 from The Latest Thing is made from Italian leather. They look great over white shirts for work (why not add a bit of kink to your office wear?!), dresses, and are useful for reining in those floaty tunic things that come around every summer.
Related: Miss Selfridge corset belt | River Island metal belt | Topshop leather belt.