In runescape you can buy a bond for some real life money and it will give you an item ingame which can be redeemed for membership or cash shop points. It is also tradable.

This is great because it allows you to buy premium with in-game money, which fits in great with the new premium model.
It also allows people to basically buy in game gold with real money, which some might argue is a bad thing, but you can already do this with the caches anyway so it's not really a downside. Seeing the direction funcom has taken the game recently I don't think they will worry about it either.