I use Dropbox, but have started to use Box. I'm not a fan of Box because their web UI is SO CONFUSING and not at all intuitive. However, I have 1T of space for life...for free.. and that's kind of hard to beat..
Are we supposed to say "LayerVault" around these parts?
Dropbox. As easy as pie.
I prefer adding the assets to the Repo using Git. Dropbox is great, I've also used Box.net and Airdrop is awesome if your in the same location.
If the project is on LayerVault I tend to keep all project related files inside it. Otherwise I usually use Dropbox.
I second Dropbox. Or third, fourth, fifth Dropbox.
+1 for dropbox + packrat to get previous files back. I still think dropbox is one of the best services around, I do pretty much everything from within my dropbox folder (books, work, sideprojects, collaboration stuff, downloads), I hardly store anything on regular folders anymore. Also using cloud app every now and then.
Dropbox, sometimes Cloud App.
I use GitHub to store all design assets (mockups, prototypes, ect) and development assets (codes and such). It's great because I have all of files locally on my computer and on a web interface. As I edit the files, I can push updates to GitHub and then my team members can get those same files locally on their computer.
The other great part GitHub is version control. If I made a mistake, I could always revert back to a previous version. There are also no disk quotas for GitHub, so you basically have unlimited storage space!
Only problem you may experience is setting it up. It can be a little bit of a confusing interface for some people. Once you learn it though, it's just a breeze!
Hope this helped!
Oh! I've used this method before and you're right, it's amazing! The version control has come in handy numerous times - also you can lock files while you're working on them so someone else doesn't go in and override your changes. But you're right, it's not easy to set it up.
What sort of size PSDs are you pushing up to GitHub? I've considered this on occasion and I don't suppose it could be any slower than Dropbox's upload speeds.