Inky (http://inky.com http://inky.com) already lets you sort by relevance. It's much more useful than VIP/whitelist/blacklist but we're continuing to play with

Inky (http://inky.com http://inky.com) already lets you sort by relevance. It's much more useful than VIP/whitelist/blacklist but we're continuing to play with the relevance metric to further improve it. It does take sender frequency into account.