If I do need to look something up, I usually just Google for it. I'll usually remember at least one phrase from the article, so I'll stick it in quotes and it pops right up.
I'm not one of those people who absolutely must be able to return to anything I've found. I figure that websites - like nearly everything else - are ephemeral, so if I can't remember one, it must not have been very important to begin with.
I usually go down to the local starbucks (I've even sat outside a large grocery store) to ask my market research questions. It's funny the perspective you gather from non tech folks.
The scene is pretty crowded and traction will be very difficult unless you have significant differentiator.
Based on my prior experience getting friends/family to use a social bookmarking service , most folks don't use any because organizing bookmarks never gets elevated to problem from a mere inconvenience. They have to shown thats it's really really easy before they become converts. Your trick is going to be how to reach this audience.