First things first: Google Docs now stores any type of file. 1GB free storage; 1TB for $250 per year (25¢/GB); no bandwidth costs.
Create a public folder
- In Google Docs, choose "Create New" > "Folder". Call it anything you like.
- Under "My Folders", right-click on the folder and choose "Get the link to share…".
- Check "Allow anyone with the link to view (no sign-in required)"; copy the "Share this link" URL; "Save & Close".
Add a public file
- On Google Docs' upload page, select a file to upload (up to 250MB), choose the folder you created above, then press "Start upload".
- When the file has uploaded, open it in Google Docs.
- Select "Share" > "Get the link to share…". Check "Allow anyone with the link to view (no sign-in required)"; "Save & Close".
- The file should now appear in your public folder.
There are URL parameters for the type of layout ("list" by default, sort order (alphabetical by default, easily changed to reverse chronological order) and number of files per page.
I expect someone will make an easier interface for this, using the Documents List Data API: more details on the Google Code Blog.