For my camera I use Adobe Bridge (from CS4) which is great, as I delete the images when I download.
But for my new phone (Nexus 4) I want to leave the photos on, and I want a downloader that only copies over the ones not already on the PC. Unfortunately I can't use Synctoy as while the Nexus appears in 'Computer' it's not a removable HDD - it doesn't get a drive letter.
Any suggestions? Free preferably, or with a free trial and cheap.