Your Dropbox public folder is a great way to share files with your friends, but if you need to share multiple files, you have to zip them up into an archive first. If you already have them in a folder, though, here's one way to share them without zipping them up.
Just stick the folder of files into your public folder, and head to the Dropbox webapp. Click on the folder you want to share, then click the "Get Link" button at the top of the page. Add
?dl=1 to the end of it, and send that link to your friends. It'll zip the file up for them and download it to their computer.
Now, in most cases it's just easier to zip the files up yourself, but this can come in handy when, say, you have limited hard drive space (and some big files) and don't want to create a duplicate of files you already have. Some Mac users have also noted that zip files created in OS X are sometimes glitchy on Windows and if that happens to you, this is a good solution. Either way, it's a handy little trick to know.
Download an unzipped folder from Dropbox's Public folder [Mac OS X Hints]