Over the next few weeks, the file type restriction is being lifted on Google Docs, so you can now upload files of any type. There is currently no way to map your Google Docs as a network drive on your PC, but I'm guessing that isn't going to be far behind. If Google doesn't do it, someone will.
Instead of emailing files to yourself, which is particularly difficult with large files, you can upload to Google Docs any file up to 250 MB. You'll have 1 GB of free storage for files you don't convert into one of the Google Docs formats (i.e. Google documents, spreadsheets, and presentations), and if you need more space, you can buy additional storage for $0.25 per GB per year. This makes it easy to backup more of your key files online, from large graphics and raw photos to unedited home videos taken on your smartphone. You might even be able to replace the USB drive you reserved for those files that are too big to send over email.
For files that aren't officially supported by Google Docs, there is a 1GB storage limit that you can add to if you wish. File size is currently limited to 250 MB as well.