Argh, I hate putting down hobbies and interests on job applications.

I'm partly a techy because I have no other interests!

But instead, I'm suppose to say I like to help Barbara work the till at the local charity shop

I don't put them at all. Mainly because there is no more space, but also because they're kinda useless

Employers are not going to hire you for your hobbies. Most really don't care what you do in your own time. Use the space to list the tech you're currently learning/researching but have no real experience of. This way you're showing that you know about the latest trends in the industry, are actively learning, and have all the buzz-words on your CV. An employer will much prefer to see your 'coming soon' skills over some bullshit love of baking and 18th century poetry.