If you want read abour rapidleech script go to rapidleech.com i will explain some main stuff that NOT included in official rapidleech.

1. Registration and download slots by group, you can specify how much can download registered and unregistred user per 24h or whatever you set. (part of rapidleech+)
2. All plugins premium logins is stored in mysql, so you can include more than 1 account for any file hosting. In original Rapidleech you can add only RapidShare multiple accounts.
3. Proxy connection for every plugin can be set separately. You can set IP1 for download from RS, IP2 for download from HF and so on...
4. Every user can transload only 1 file at the same time and after transload must wait some time to start transload again. This option will reduce server load, traffic and generato more revenue.
5. Detailed admin pannel with stats, config options and other stuff (part of rapidleech+)
6. Some stats on the main page.