Maybe a bit specific, but for anyone who took out a £15 for 500 minutes a year and a bit ago are now eligible for a free upgrade at 15 months.
I took this contract out in March 2007, and have just rang them up to see about upgrading.
They offered me a brand new (not a refurb!) Nokia N95 8GB Black on a new 18 month contract for £15 a month.
I'm sure this cannot be beaten.
Available by ringing 333 and talking to upgrades.