Think if you had a customized subreddit that brought in things from several websites
Needs pluginability to cull from several sites with ones easily added
Could use something like Embedly (or an open source alternative) to present reasonable previews
Needs all features of an inbox including pinning/starring, grouping, filtering, deletion/manipulation, prioritization, sorting, etc
SaaS or no-SaaS?
SaaS pros: access from everywhere, possible social component (i.e. shared "directories")
SaaS cons: legal (e.g. responding to DMCA), costs
It needs to have the most ridiculously non-fancy iface, so if SaaS, basically craigslist w/ JS features but must have noscript fallback with almost full feature support