I don't think there's a site dedicated to that purpose specifically. However, Untapped and Beermenus are probably your best bets. I've never used Untapped as I do not have a smartphone and I think they've just recently added desktop/laptop support, but I have used Beermenus. It's ok, not great though. Again, it's really up to the brewery/bar to update their menu and sometimes they just forget; they're human too, despite being able to brew some godly beers.
But in general, this question is a bit too broad. in my opinion. You don't specify whether or not you're talking about local beers or just beers in general. There's a few thousand breweries worldwide; many of them coming out with new releases regularly. Keeping tabs on all of them would be somewhat of a challenge (especially the ones who don't update their sites regularly (ahem...if my local friends across the bay are on here, I'm looking at you). So in terms of local beers, Untapped and Beermenus should do what you're looking for. But At this point in time, I think a global list is infeasible until somebody develops an easy-to-use API which gets some traction in the industry.