From the casino’s point of view – it’s real time referrer stats.
I often give programs that offer these top placement during a new campaign because I can pop over there all the time and see how the campaign is doing and adjust as needed.
I do this even when the program doesn’t normally produce results that warrant such placement.
From my point of view – I like custom banners that will say for instance:
$50 matchbonus at GamesandCasino only!
or something of the sort.