Web application single-sign-on

Question

Hello my people,

Please help!!

We are planning to buy a Single-Sign-On application that we can easily plug-in into our applications from any reliable company.

At the moment we have few sites websites hosted on different domains and developed with different application (asp.net and php).

Please I would like someone to introduce any good company that can help us implement a single-sign-on. Most importantly it must be easy setup in dot.net (mainly c#) and (Drupal Php).

Please note users data are hosted on a separate SQLSERVER database for each site and php site is using MYSQL database. The system must work across these entire domains.

We are not look for a developer or software house all we want is company to buy the product.

Thanks