The Orange World WAP service is offering 15 FREE Comic Relief calling tunes (it's the tune you choose people to hear when they call you) and they'll donate 20p when you get a tune. Seems a great deal to me - getting something for free and donating to Comic Relief at the same time. Some good stuff in there including Monty Python and Lily Allen.
You need to be an Oragne customer to get this. Just go onto Orange World on your handset (sorry - not on internet at the moment) and go to the 'Music & Tones' section. Calling Tunes is in there and you'll see a big banner for Comic Relief.