How about book vouchers? They can be spent at independent book stores
if people choose to support them. Most people have some kind of
independent book store near them. And knowing the wikiholics who might
win 'em, the money will eventually come back to improve Wikipedia as a
fair number of people will use them to buy reliable sources and then
edit articles on the topic.
If someone is likely not going to be able to spend them, we include a
very small proviso saying something like "if the prize is not likely to
be redeemable, Wikimedia UK may at the discretion of a member of staff
or the board of trustees (delete/edit as politically appropriate this
week) provide a similar prize of equivalent or near-equivalent value".
A hack day I went to a few years ago had a really amazing prize: two
tickets to the British Museum's then current special exhibition. This
is one of my favourite hack day prizes. It wasn't a big and expensive
prize like some other hack days offer (iPads, foreign travel,
significant amounts of cash etc.) but it stands out precisely because
it prompted me to go to an exhibition that I wouldn't otherwise go to
and learn about something I wouldn't otherwise take much of an interest
in.
--
Tom Morris
<http://tommorris.org/>