iOS does pretty well with handling various file types, but when it comes to compressed files, you run into problems. Fortunately, with the aid of a file browsing app you’ll be able to view compressed files easily.
Lifehacker reader willeemammoth points out that you can get your iOS device to download ZIP and RAR files with the aid of a file browsing app like USB Disk.
While testing USB disk, I inadvertently found this was also true of Air Sharing. The benefit of USB disk, however, is that it’s free (with ads). The benefit of Air Sharing is that you don’t have to connect your iPad to your computer should you want to transfer over any of the downloaded files (as Air Sharing is designed to do that over Wi-Fi). Thanks willeemammoth!