Google maps, how I love them! Easiest way to plan a quick trip or some not to be missed site on your vacation. I especially love the new walking directions option since I am very anti car in the city! Google also let you drag and drop to change the route on the map, useful.
As far as the uploaded pictures, it's useful to get a feel for the area you are headed to, not to mention being able to identify the building you are looking for.
I've used Yelp a little bit, is this where I mention that I'm a weirdo who appreciates when folks out there take pics of their food and publish it? Well, it can help when trying to figure out if one restaurant is what you think it is or very much like another you really like. Odd, I know. But this is what I did when I decided I wanted to try shabu-shabu or hot pot in Chinatown. New to the whole thing I wanted to get some idea of what to expect. The reviews were great and answered alot of questions, like the big one I always have to cover....vegetarian options? But there really is nothing like a photograph! The photos actually helped me figure which place I wanted to try and did steer me clear of a couple. I haven't posted a photos on any of these sites but I can see myself adding one to a site like tripadvisor to add to one of my reviews. I think that would just make the review all the more useful. Until then here's my shot of hot pot...with a little sake of course!