i perfectly understand that Omni relies on itself even though there might be useable and useful solutions out there, created by 3rd party devs.
that's why i don't present my suggestion here uncommented.
as much as i am looking forward to an inhouse solution of Omni for this feature, add blocking for me is no issue any longer.
i'm using BFilter (see the ad blocking thread on this forum:
http://forums.omnigroup.com/showthread.php?t=2032).
the latest version of it is fast and eliminates all annoying ads without the risk of accidentally launching a hidden link by clicking on it
BFilter info:
http://www.macupdate.com/info.php/id/20181