Contutto is a plugin that creates an affiliate shop inside WordPress with CSV data from Affili.net. It features an intelligent template system, a powerful search and fully automatic CSV synchronisation.
Contutto is available under the GNU GPL. (The basic version is free to download, while the premium version, also GPLed, is only available with a support package.)
Note: Only tested with German Affili.net. I tried to open an account with British Affili.net, but they seem not to accept German applicants. If British Affili.net users want to try it, let me know.