I think this topic was covered about a month ago in another FD thread. I just spent a fair bit of time looking at this and after a bunch of reading a cease-and-desist, my conclusion:
* High probability that the site's license will prohibit you from using the content the way you want.
* US courts have generally ruled that site's license isn't enforceable because it's not reasonable to expect that the user has actually read it all
* US courts have flip-flopped on hot-linking (where you embed content such that it looks like it's on your site but is actually hosted elsewhere). The last flop was a more permissive ruling that allows folks like Google to display thumbnail images as long as they don't host the content. My understanding is that the EU is much more protective of content owners' rights and hot-linking is just as bad as hosting content.
* None of this really matters because you're not going to fight Ask.com or About.com because they have much more money than you and will bury you with legal costs.
* So I'd suggest trying to figure out how you can make it good for them (e.g., provide their branding and show how it'll drive traffic back to their site) and either (a) get their explicit permission or (b) have a plan B when their lawyers come knocking.