#2 - March 21, 2010, 3:06 p.m.
Tandaa is correct, Hemloch. When two accounts are linked via the Recruit-A-Friend promotion, the recruit account can grant one level to a character on the veteran account for every two levels the recruit gains. Additionally, while partied, characters on linked accounts can gain bonus experience and reputation, as well as summon each other great distances.
There are certain restrictions for granting levels and the other Recruit-A-Friend bonuses, and these are all detailed in the Recruit-A-Friend FAQ, located below. I’d very much recommend giving it a read in order to get the most out of the RAF promotion.
Recruit-A-Friend FAQ http://us.blizzard.com/support/article.xml?locale=en_US&articleId=20588