Web Content Management: one of the difficulties I saw customers faced with were moving data from their existing sites, based on "old" engines or even static, to desired Web Content Management systems, like Sitecore CMS. Often they dropped an idea of upgrading just because didn't want or couldn't put efforts to just moving the existing content.
I've just seen the demo by Stephen Moore from Kapow - "Migrating Web content into Sitecore: 8 Minute Demo". Now moving data to Sitecore becomes easier. Interesting things that data can be taken even from front-end of the existing site. It worth seeing!