The work I'm currently doing at the Open University's Biodiversity Observatory is part of a much bigger project called Open Air Laboratories (OPAL). The aim is to encourage more people to find out about their environment, get involved with the science associated with environmental issues, and learn more about wildlife and conservation.
One of the (many!) activities that OPAL is promoting is a series of public participation surveys, and the first of these is now up and running. It is devoted to soils and earthworms. The survey asks you to select a suitable site, do some simple tests to assess the nature of the soil, and find and identify a range of common earthworm species. You'll need to do a small amount of digging! The results are posted online and can then be seen on the survey map (some are appearing already).
In terms of biological recording, earthworms have been rather neglected in this country, perhaps surprisingly given our penchant for recording other rather obscure invertebrate groups, and at the moment there is no recording scheme nor published atlas for earthworms. The OPAL survey provides a well-illustrated Field Studies Council key to 12 common species of earthworm (download from the OPAL links given above), but if you want to take things further and look at the full range of species the Natural History Museum is seeking volunteers to undertake full surveys of worms in natural habitats. Training in the use of the full key by Sims and Gerard (1999, Synopses of the British Fauna, [currently out of print] UPDATE: now back in print) will be given. For further details of this, contact:
Dr David Jones, Soil Biodiversity Research Group, Department of Entomology, Natural History Museum, London, SW7 5BD. 020 7942 5706 or dtj [AT] nhm.ac.uk
While we're on the subject, there's a lot of good information on earthworms at the UCLAN Earthworm Research Group, and some fun video footage of Lumbricus terrestris at ARKive.