Ziplight can be a godsend if you work often with ZIP files.
This little plugin works perfectly with Spotlight, allowing the Mac search function to look within ZIP files to find archives, whether these be documents, photos, videos or anything else. That way, you won't have to unzip every compressed file you receive just to verify what is in it. To note though, Ziplight doesn't exactly search the contents of a Zip file but only looks for the name of files. You'll still have to know more or less what you're looking for in the compressed file.
The real strength of the plugin is how it makes use of the speed and reliability of Spotlight, which can quickly find any file and learn from the queries you make. Once you've installed it you'll have forgotten it's there and finding files in a Zip archive will be a breeze. It does make you wonder if Apple will include this functionality in future updates to Spotlight though.
Ziplight is a useful little plugin that allows Spotlight to look for the names of files inside of Zip files.