Gifts you can print or send electronically
I have been thinking that there should be a place on the web where someone can go if they've had a serious 'fail' on Christmas (or otherwise) presents. Stuff that can be bought online but that allows you to print something off, or email someone a voucher code, or even just print off and play with, or colour in (for the kids!).
"E-mail or print a gift card, or send in a greetings card, gift box or multi-pack. Redeem Amazon Gift Cards for millions of items storewide."
- hat tip @philbradley . Don't forget that if you'd normally give someone a £10 book you might need to give them a £15 voucher so they don't have to pay extra for postage and packaging :)
iTunes vouchers for music (iTunes store) or apps (app store) - I am not sure if you need to have iTunes on your computer though or if you can do it via other shops, eg Amazon.
Lend with Care (from CARE)
http://www.lendwithcare.org/gifts/ - charitable microcredit sort of thing, see also Kiva
Toilet Twinning (donate to projects to build loos to improve sanitary conditions)
Classes, memberships and subscriptions
I think you can print out vouchers for cookery or photography classes and things of that ilk. Also memberships of various organisations.
Printable Christmas crafts including 3D Christmas snowman and tree
General Christmas printables
Christmas baubles (£2.95 to download, but there's enough info to make your own)
Christmas gift tags