We recently covered the Sega Dreamcast hard drive modification (here) but today, we are reporting on a new mass storage option. The Sega Dreamcast is getting a USB mass storage option that replaces the GD-ROM drive altogether. Since this is an USB option you are not limited to the size of SD cards (about 128 gigs is the biggest right now). Instead, the USB-GDROM Controller will allow you to plug in up to a 2 terabyte hard drive (that will hold a lot of homebrew).
The Sega Dreamcast has received updates that have allowed a couple of add-on storage options in the past but this one is the most interesting. The USB-GDROM Controller also comes with updated software and USB 2.0 speeds (no USB 3.0, yet).
Right now, the availability of these add-on boards is quite limited, more so than Atlantean is. More are expected to be available in the future.
Prices available on the USB-GDROM website.