Just started using Dropbox to sync between my PC, server, Android phone and the web, it really is great. Easiest and simplest syncing solution I've found.
Had been thinking about it for a while, and then it was Gina Trapani (of TWiG fame) releasing her new Todo.txt Touch Android app that finally convinced me, as it uses Dropbox to do the behind the scenes updates.
If you sign up for Dropbox please use my affiliate link Sign-up for Dropbox as it will get us both an extra 250MB of storage on our accounts for free. Thanks.