GoogleDocs now gives you the ability to upload any file type, store it online, and share it with others. You can upload anything (audio, video, images, text, etc.), but you can also continue to convert certain file types (spreadsheets, word processing, presentations, etc.) to formats you can actually edit within the Google Docs application suite. There’s a size limit of 250MB per file, and you have a grand total of 1GB storage space (per gmail account, but really, who has only one gmail account. Am I right?)
Anyhoo, this can replace email when you’re trying to get documents to other people–especially when dealing with large groups of people or with files that are too large (20mb+ usually) to email. It can replace services like yousendit.com (which has a size limit of 100MB per file–unless you want to pay their monthly fee and send a 2GB file). It can replace your USB flash drive, which you have to worry about losing, or forgetting to bring with you.
And one of the most powerful features for me is that you can share these files with anybody–either just with select people that you specify, or with anybody who has the link to your file.
More info on the help page at http://docs.google.com/support/bin/answer.py?answer=50092