They've got the world's only flyable Vulcan bomber and they offer something that anyone (who wants it) can download for nothing on the web.
Incentives aren't always easy to get right, but experience has shown me that people won't just download or sign-up to ANYTHING in return for a donation, even if they are passionate about the subject. You really need a "money can't buy" to trigger donations this way. I learned this the hard way with 10 years experience of marketing to football fans - their support isn't as blinkered as you might think!
Surely they can come up with something original?
Calendars often seem to do well actually - did they do a 558 2008 calendar with some specially commissioned photos? I'm guessing not - but it's one thing that could have exploited the post October euphoria following the first flight and the run up to Christmas. I hope they did...........but not holding my breath!