I have a table with a whole list of sites, and then each user can add those sites to his account, so basically i want to create a field in my users table that stores all the different sites that a person has added to their account.
It's similar to facebook and adding friends...

The best way i can think of to do this is storing the different id's of the sites in an array in one single field - don't know if this is possible or if there's a better way to do this?

Also, then how would I retrieve this list of sites in array form and then how would i add another to this list?