The ATC has been using a system for accepting registrations for workshops that I developed a couple months ago. It can be seen here:
The list of workshops is managed by two text files. This allows the content to be easily updated, since it only requires an FTP password to the folder containing the text files. Editing text files is straightforward and requires no special software. This approach was chosen over a database-driven system so that it would not require a special user database to be managed.
When a registration is submitted, it logs to a third text file which includes all the user's details. The text file can be opened directly in Excel.
This has proven to be an effective and easily maintained system.