The 1.1 version of QuickNFO for Mac was available to download on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The application belongs to System Tools. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. This free Mac app is a product of GitHub Inc.
From the developer:
Max OSX QuickLook Plugin for previewing NFO files
Uses libiconv to convert the nfo text to utf8 and then lets WebKit render the output. Seems to work well (at least for the few cases I have tested).
The current version supports preview and thumbnail generation.
You may want to check out more software for Mac, such as iBatch for iTunes, Audio Plugin Player or MiniLyrics, which might be similar to QuickNFO.