Resources in Career Gateway
Volunteer - a Traveller's Guide to Making a Difference Around the World (Lonely Planet) features over 170 organisations, listed and reviewed in a user-friendly structure arranged by type of volunteering programme.
The Gap-year Guide Book 2011 (has sections listing organisations) provides useful, informative and unbiased advice for those considering a gap-year.
Green Volunteers (world guide to voluntary work in nature conservation) is an easy to use resource for prospective volunteers interested in environmental work worldwide.
The Voluntary Agencies Directory 2007 (National Council for Voluntary Agencies) Although an old resource now, may still provide valid information about charities in a wide range of area