I installed the Memory Zone app on my Droid 3. It started up quickly and accurately reported the memory information on both my internal (phone) and external micro-SD card. I linked all four of the currently available cloud storage sites, within Memory Zone, and again the cloud storage space was quickly determined. I encountered no problems with the app.
Presently, Memory Zone only supports the cloud services of DropBox, Box.net, Google Docs, and Picasa. I hope the plans are to increase the number of cloud sites that can be reported through this app.
I am going to suggest that they expand the cloud services to include Windows Live, SugarSync, ZumoDrive, and Amazon Cloud Drive.
This is based on my experience and my opinion, most likely yours will differ.
Bob