Having been one of the fortunate few to have had a sneak peek at the late closed Alpha of Hackaday Projects I would say it's definitely a website to visit and visit often. It's already jam packed with great projects, that you'll probably see there first as they're often not completed at the time of publishing.
It's my belief that this site fills a yet unfilled niche in the hacker / maker world. Somewhere to actually work on projects, rather than a pedestal to put your shiny finished products. Sites like Instructables and Thingiverse put you in the part of the creator of a thing who wants to share it. Hackaday projects puts you in the place of someone working towards a thing, where people can help you out along the way with a kind word or even collaboration on your project. It's like a big online hackspace where everyone is working at their own bench but every now and then look over and say, "hey that looks cool" or "want a hand with that?" or quite possibly "why on earth are you doing it like that?" or "whoa! You're going to lose all the fingers on your left hand".
The site is new so expect a few glitches and for it to be a bit clunky at times, but it seems that the team working on it are doing so proactively and there are improvements happening all the time. They've also just launched a competition, which is something we all love! To build something SciFi themed with a collaborator. I do have an idea in mind...
If you do decide to stop by please check out my page, I'll be working on some projects on there and posting up the details of some of our previous ones too. I am hacker number 654 or there's this link if you prefer.