Few details about projects using BOINC and few words about client.
The client
The BOINC Project (Berkeley Open Infrastructure for Network Computing) it's a piece of software, called client, which is installed on your computer and feeds himself with chunks of data , called workunits, downloaded from the project''s home server. After processing a workunit, the client sends back the result and fetches a new workunit. And so on... The client can be configured to run when your computer is idle, so it will not affect your computer''s overall perfomance.
Projects
The full list of the projects using BOINC client can be found here.