This is really great!
Years ago when I was still in college (so probably before 2001) I had this exact same idea, but not the skills to implement it. Later, still wanting a searchable archive of pages I bookmarked, I wrote a Perl script that fetched every link in bookmarks.html into a SQLite database and indexed the content. It was very hackish and not very smart (just indexed the raw HTML), but it worked for my needs, kinda...
After a few years switching laptops and using multiple systems, I let it fall by the wayside - copying the DB and scripts from one system to another and keeping them all in sync was just too much of a PITA to be worth it to me... I'm still a rabid bookmarker though, and your service looks like the realization of all the stuff I wanted to do!
If you offer a free-trial (say two weeks) of this service, I am very interested in trying it and would certainly provide plenty of feedback. I'm not yet convinced that I want to pay $3.99/month, but I don't think it's an unreasonable amount at all, especially considering the iOS app, planned cross-browser support, and the very slick-looking interface.
Add to the existing features some mechanism to automatically/transparently sync new bookmarks, and add some assurance that the data is stored securely and encrypted, and only used for new things with my express permission, that $3.99 goes from maybe to deal!
I'm excited for this - I see a viable business in it since I know I'm not the only other data-packrat out there.
EDIT: I just saw the trial voucher and used it. Thanks!