Bumper Shine!!

[00mike00]

boiled linseed oil is my tip, dont let it dry on the paintwork though

I came here to say exactly that. I'm sure that any 'product' you buy for your car to do this isn't going to last as long. Otherwise you wouldn't buy anymore!
Linseed oil not only impregnates the material but creates a waterproof barrier, which in turn keeps things black. CHEAP!

[whiteshark]

I'm not into shows and I hardly ever wash my car unless you can't see the paintwork, but for bumper shine I highly recommend C4 Permanent Trim Restorer. Used it on my Mk 3 Golf and the bumpers came up a treat. Not cheap, but the results speak for themselves. Available on the bay. A small bottle goes a long way. Do not spend a fortune buying a large bottle unless your into concours.

[unknownmale]

I recently used the carplan spray which worked well