We organise our work into a variety of separate projects, each of which is controlled by a member who has volunteered as project manager. The manager splits projects into separate smaller tasks and estimates roughly how long each task will take. He also states any special skills or knowledge that members should to complete the task.
We are also compiling a directory of Altruists on the Web, so any time you've got a spare moment you can suggest an altruistically motivated site. Members who have successfully suggested several sites can become an editor and take control themselves. Members with language skills can also help translate this site into different languages.