Just stumbled on to this, thought some of you might want it as well.
http://www.applicationgap.com/
"Easy Release by ApplicationGap replaces inconvenient paper release forms with a slick, streamlined application designed by professional photographers for professional photographers. Easy Release lets you collect all the data and signatures you need right on your iPhone, then mails a PDF and JPEG of the release right to you. Easy Release builds-in industry-standard and proven legal language that is accepted by the world's leading stock photo companies, like Getty Images and ALAMY but also let's you add your own custom contract language! Plus, Easy Release supports 13 different contract languages, and 7 UI localizations* so you can get the release you need, no matter who, or where you are shooting. Now with unlimited user-defined releases and branding header with logo!"

I wish I'd had this at the last thing I filmed. The paper work got rained on, and turned to mush. I couldn't hand it to anyone to sign.

http://www.echosign.com if you want, let people sign it and confirm it with a bit more than unverified details (which from a legal POV are pretty much worthless)

And, what condition would the iPhone have been in, if it got rained upon?

Pricey though!
I'm not sure what you mean by the legally worthless though?
You have a form, describing the usage of the picture/video to which they sign their consent. It's a form of contract.

Yes but a digital signature (as we found out on a project we did for a solicitors, ended up using echosign) isn't worth the paper it's figuratively written on, it's completely admissable as a legal document should someone wish to challenge it apparently

Why they didn't make a more legally binding one with something like echosign (especially given the £6 cost) and then they could have moved their model to a pay as you use system

Did another project with a drawn signature, but it's worthless and is just there for show more than anything

Ah right, so it's the fact that it's a digital copy of a signature rather than the real deal that's the problem?

The problem I have with Echosign is the cost.
For that much, I'll stick with pen and paper in the future. And invest pennies in a plastic sleeve for the wet days.
Even if I hand draft a quite 'I, the undersigned, give my permission to _______ for the use of my image in __________ capacity in perpetuity', and get a signature, I think I'd still be ahead.
For a lot of events, simply using a blanket statement about recording and your attendance gives permission works well too.
£6 a month compared to the £7 one off for Easy Release.

Echosign just isn't built with release forms in mind, as far as I can tell.

It was the problem we had trying to get a developer account

The thing is it wouldn't be you that would have the account, it would be the developer of the app, distributed across a few (say 5 or 6) templates for all users on their account, that way you don't get customised forms (to start... you could add it later) then the user can fill in name/email/dob, authenticate with a facebook account or google account and get digital copies of all documents

So instead of a £6 app you get (say) a £2 app and pay say £10 or £20 per 100 documents you get signed with your first 5 or 10 free, then as a developer they can get a decent injection of cash for the service, provide a more customised service for higher paying customers (those that want unique docs) and uses a recognised service