For more than thirty years, Marilyn Megenity's Mercury Cafe has given this city a movable feast of good works, good food and good entertainment — much of it free. For the last two decades, the Merc has been doing it from the edge of downtown, in an area that was once sketchy and is now heading toward respectability. And you'll find both sketchy and respectable types at the Merc, where first-date diners sit next to Occupy meetings and poetry slams collide with tango lessons and live shows in the underground community space. From morning 'til night, you'll find everything from dance to yoga, jazz to cello, with no charge for many programs. And the food, if not free, is locally sourced and made with care. Just eavesdropping on the conversation one table over could qualify as the best free entertainment in town — but at the Merc, there's always some rising talent on display, too. And if you don't like any of that, you can always grab a free book from one of the Mercury's shelves.