backup program for backing up only modified files | 'snapshot'
I'm planning to set up a fileserver for my own use next week and because it will have all of my files centrally located (finally!) I will be running regular backups from there, probably using cron to do it every night to one of my other computers and/or a flash memory module for the stuff I really care about. My question is what is a good Linux program that can be used to backup or create a 'snapshot' as I think it's called of only the files that have been modified/added that day or whatever.
Also, because I carry a lot of files I use daily on flash memory with me to school, is there a program that can use to 'sync' the flash memory with my server or highlight any modified or new files in the flash memory for me to transfer over?