Video and photos are trickier, but for music I use Google Play Music. I installed the app on my Mac, allowed it to upload all my music to Google's servers, then I play it from the Google Music app on my phone. I can store local music and stream what isn't stored on the phone. Works great and I have access to virtually everything.
Another option is DoubleTwist with AirSync for wifi syncing, though I never got it to work on my GNexus. Other people however seem to have good success. I believe this will do music and photos. Not sure about video.
For video, there's always drag and drop, though automatic syncing would be nice.
I look forward to hearing what other people suggest.