The internet. It's not just for looking at snatched photos of former pop stars emerging from hot-tubs, you know. You can use the power of the web to make a real difference. Here are some ways:

1. Agitate, educate, organise

Want to share your concerns about a local problem, or find people who care about the same things as you? The first place to try is the BBC's Action Network. Here you can find who's campaigning in your neighbourhood, post a notice about a forthcoming event, and make your voice heard.

2. Speak truth to power

Need to bring something to the attention of your local councillor, MP or MEP? You could try Write To Them, the successor to the popular FaxYourMP service. It'll take your postcode, give you forms to directly contact your elected representatives, and offer suggestions on the best approaches to take.

You can use their sister site, They Work For You to see how your local MP is performing on the floor of the House (and if they turn up), and to add your comments to text of parliamentary debate.

3. Donate as you search

Most search engines exist not out the kindness of their hearts, but to make a few quid. The money you raise as you seek out the name of a local plumber doesn't have to go to fund another new Porsche for someone in living in California - there are now a number of services which donate some, or all, of their profits to charities. For example, Everyclick allows you to choose to donate to any UK charity every time you search; some charities offer their own search services.

4. Help crunch some numbers

Your computer is a powerful calculating machine. Most of the time, though, its capacity for doing sums is barely tested - so why not use all that spare capacity for something? Not only will your computer be delighted to get a workout, but you can help with some huge projects that link up a number of users to create a virtual supercomputer. You could assist SETI look through data gathered by radio telescopes hoping to spot evidence of life beyond Earth; Rosetta sifting figures as part of a search for a cure for cancer or even Leiden, exploring classical dynamics. Distributed Computing offers a list of active projects looking for volunteers.

5. Join an online campaign

Many major charities have seized the power of the web to energise their campaigns - perhaps the highest profile example being Make Poverty History. The ability of the internet to quickly mobilise large numbers of likeminded people makes it a great place to make a difference - the National Council of Voluntary Organisations explains some of the advantages.

But does it work? The WWF believes it really does.

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