Roberto, I haven't worked with a Mac in years and can't address your question about using Easeus on one. However, as noted in post #516, if you have access to a Windows computer and use Easeus, you can regain the memory. The procedure is very well detailed in the online instructions for Easeus. I followed them exactly after reading them over a couple of times and figuring things out.
Basically, I just inserted the sd card into my laptop card reader, started Easeus, located the drive letter corresponding to my card, ran chk disk and defrag, then selected the partition that I wanted to extend. It was easy to select because I knew how much memory the Nook Color was reporting for it. Right next to it was the unrecognized partition and about 5.94gb of memory. After right-clicking on the appropriate partition (the one just before the unallocated partition), I selected Resize/Move and just moved the right side limit bar over to where I wanted it. I left about 679gb unallocated as per instructions so the program would have some working space. Then I clicked OK, and then clicked Apply in the box at the bottom of the wizard column to the left. Voila! I now have gone from 1.24gb available on the card to almost 5gb (as reported in the Nook Storage settings).
My computer still reads the size incorrectly, but since I can now download audiobooks, etc., directly to the card from the nook, I don't rely on sideloading at all. HTH
I used Easeus on a Windows box and it worked great. I thought that gparted on Linux might work, but it didn't see the SD card although the computer recognized it. I now have 13.4 GB on the virtual SD card when running Honeycomb on the NC.
