Zip-online is a free web-based zip software that lets you zip up to 5 files online and then download it to your PC or send it over by email. No installation or sign-up required. The only limitation is that individual file sizes can’t exceed 650 KB, that’s all. And since it’s an online service it works both on Mac and Windows computers.

Additionally, if you’re a developer and would like to install similar PHP script on your own website and offer your readers the same functionality then you can download the script from here. It’s easy to install and manage.
There is also a service called Wobzip. It does the opposite of Zip-Online and allows people to upload and unzip archived files online. Quite useful if you need to uncompress the archive file that is not supported by your main archive manager (i.e. Winzip or Winrar). Wobzip works with 7z, .ZIP, .GZIP, .TAR, .BZIP2, .RAR, .CAB, .ARJ, .Z, .CPIO, .RPM, .DEB, .LZH, .SPLIT, .CHM, and .ISO formats.
Check out Zip-Online @ www.zip-online.net