I tried your new "favorite sweeps websites" function thing just now and noticed that in the case of sweepstakes advantage or sweepstakes plus, links for sweeps would normally open in a new window but in ninja you can tell the link is being checked but a new window isn't opening (ie: <a href="goto-new-url.com" target="_blank"> )... you need to have a split screen or something for url new tab/window redirects.
Also while not a bug it would be nice to be able to see pages in their entirety (like full screen) in the preview pane. I find scrolling left, right, up and down because I only see quadrants of a page really annoying. It's actually easier for me to view a url in firefox before adding a sweep so I don't miss anything scrolling around in ninja.