Simple idea and addictive: FILMography holds up movie stills (recent and vintage flicks) up to the current location.
I Want More Food is "awesome food, cultural, rad, and other experiences in New York – specifically Queens." Lots of interesting finds and great fun to read. Pictured: the handiwork of street vendor Tortas Neza.
There's a free version of Old Maps: New York but spring for the $1.99 full app. Reward: over 150 vintage maps of the city over time. Available for iPhone and iPad.
FeelDay is a beautifully designed site scouting the best family activities in NYC.
An encore hat tip to The New York Nobody Sings where everyone from Dylan to Johnny Rotten to Babs Gonzales to Clap Your Hands Say Yeah make an appearance, dedicated as it is to the songs of NY, with this proviso: the songs must be 'brilliant' but 'not blindingly obvious'. Great site.