Check out TimeBank, a national campaign that raises awareness of volunteering. Aimed at people who want to volunteer but don’t know where to start, it guides you through the opportunities available, includes stories about the experience from people who have volunteered, and provides directories of areas where you can get involved, whether locally, as part of national campaigns, or overseas.
Do-it offers a searchable database that provides details of volunteering opportunities in all kinds of fields in your local area.
Idealist provides a similar tool for finding opportunities in the UK and overseas.
The Charity Commission for England and Wales, the government department responsible for the charity sector, provides a list of all registered charities on its website.
Of course, if there is a particular organisation whose work interests you, just pick up the phone and give them a call – no doubt they’ll be happy to hear from you.