If you're anything like me clients are forever loosing the projects you hand then on DVD, Data-DVD, CD, Flash Drives, copy to their hard drive, hand them hard drives, upload to their FTP server, can't figure out file hosting sites CAPTCHAs, etc... ad infinitum.
SO...it just happens that box.net, a competitor to DropBox is offering for a limited time a full 50 GBs of storage FREE just for signing up.
You see where I'm going with this; while box.net doesn't have the Finder integration that DropBox does (and face reality, the client likely can't figure out anyway) it does have oodles of storage and an easy to use web interface and iOS compatibility (meaning your iPhone and iPad and iPod Touch).
You can upload a completed project to a box.net account, send (email) the client a URL to the file for them to download and then wait for the inevitable codec incompatibility calls to come in as per the usual.
But, at least they'll have the file and an email (which they'll lose) with a link to the file. Just make sure you Subject the email with the project name and the word "download" and yeah, I just used subject as a verb.
Better yet, create a box.bet account FOR THEM using their company so later on you can blame it all on them.
Update: To get the free space you may need to sign up with an iOS device like an iPhone or iPad, if you don't have one try it on a friends or run into an Apple store and set up the account.
I'm like that :)