I think it would be nice if players that have played for a long time should get something, like a t-shirt costume or a new fun costume weapon that will only be obtainable through this way, and ofcourse account bound. Give a gift for each year an account exists, the longer you play the better the item you get ofcourse
The data for this should be obtained through Warpportal Account Info.
http://puu.sh/7EX7k/5d89ac828f.png