I use Degei for my tracking, and iHerp for a bit of showing off, and for its lineage database, which is invaluable in my opinion.
So sorry to tell you that your idea's already been done, lol. If you want to make a site like the one you're suggesting truly useful, focus on enabling it to read the backup files of the most popular offline herp tracking databases. If I could upload a file and all of my Degei data would be on the web, I would definitely pay attention to that.