Global user database

Hey,

For the moment i use different tools on our website. These are provided by our provider through cpanel.
The things i use are:
- forum, phpbb2
- shop, OS Commerce
- Photoalbum, Coppermine Photo Gallery
- Shop, PHPauction
- Kalender, WebCalendar
- Chat, phpHeaven
- Links, phpLinks
The problem now is that these all use seperate userdatabases. Is there any possibility that i can 'link' this all together?
I don't have much knowledge about programming in php/sql, so i should be simple.

Nobody has an idea for this?

Maybe it's possble to link the tables in de SQL db? I don't know if we can do this?

I was going to point out that this post is almost a year old, then I realized it was YOUR post...
After a year you still haven't found any solution?

I think this is an interesting question, and likely useful to many other websites.
The idea of a Single Signon system would definately help you out.

However these projects are all developed by different companies, so the chance that they've created a user-sharing aspect is somewhat unlikely.

I've never heard of this type of thing asked before, but it makes perfect sense.

Perhaps the most ideal solution is to develop your own system. Obviously this costs money and involves a huge commitment of time.