Google-drive – How to synchronize Basecamp and Google Docs automatically

http://docs.google.com/support/bin/answer.py?hl=en&answer=58225

"Keep in mind that it's not possible to email multiple docs as attachments."

Looks like your only option is to download multiple docs (More Actions > Export > Download) and attach the resulting zip to an email ... or to go through the "Email as attachment" process multiple times.

You can try cloudHQ for Dropbox: http://cloudHQ.net/dropbox This service synchronizes Dropbox with Google Docs. Also there is a Google Chrome extension which enables you to manage (copy, move, etc.) and even edit Dropbox files directly from a Google Docs interface: https://chrome.google.com/webstore/detail/iobcbdgacfkninlcbphihhdlkobkehia