From now until a minute before midnight on Sunday, or until supply runs out (probably the latter!), you can save up to 25% on iTunes vouchers with PayPal Digital Gifts.
Specifically, you can grab a £15 iTunes voucher for £12.75 (15% off), £25 iTunes voucher for £20 (20% off), £50 iTunes voucher for £37.50 (25% off), or £100 iTunes voucher for £75 (also 25% off).
iTunes vouchers can be redeemed on the iTunes Store, App Store, iBooks Store and the Mac App Store.
(Thanks to zips at HUKD)