Some time back posters were on this thread and agreed with me that the Maybelline sponge ball tipped concealer was very good but it was too big.
Revlon have brought out one. Again it is a round shape sponge tipped concealer but it is smaller. It's really good. More under eye shaped than the larger Maybelline one.
The Revlon one is worth a try if you have dark under eye circles like me.