While packages.gentoo.org is down, I don’t enjoy it more than anyone else, but if you are really craving to browse the portage tree through a website, might I offer up GPNL as an alternative.
It’s definitely not as sexy, it’s searches aren’t that great yet, but it is functional. Plus I just setup a cron job the other day to do daily complete database dumps. So if you want to build your own, there ya go. The postgres schema is full of stuff like foreign keys to enforce referential integrity, which is a good thing.
Feedback is, of course, welcome, but I haven’t had time (or made it) to work on the project in a long time.