I've downloaded Droid Sans, Droid Serif, and Droid Sans Mono fonts from google.com/fonts and the first two have installed just fine.
OS X 10.9.5. I'm extracting the font file from the download ZIP file, double-clicking the TTF file, then clicking "Install".
Unfortunately, I can't get Droid Sans Mono to install; it looks like some message boxes pop up very quickly, but I can't read what they say. When I validate the font file, it looks okay, but installation doesn't do anything.
Using the Console app, the following messages appeared during the time I try to install the font:
4/20/15 1:36:22.068 PM taskgated: binary have embedded signature that validated /System/Library/Frameworks/Quartz.framework/Versions/A/Frameworks/QuickLookUI.framework/Versions/A/Resources/QuickLookUIHelper.app 4/20/15 1:36:22.105 PM QuickLookUIHelper: LSExceptions [0x7fe5f0707e30] loaded 4/20/15 1:36:22.112 PM Finder: LSExceptions [0x6180002b4640] loaded 4/20/15 1:36:22.125 PM lsboxd: Connection from pid 24856
Any idea what I might be doing wrong?