I was looking today for the most convenient way to download the MODIS landcover data from the LP DAAC. In between the 7! different portals one would expect at least one to be easy, but it was only the 8th option that turned out to be really easy; the Reverb portal. It is in beta and I only found it when visiting one of the above-mentioned portals, the WIST (Warehouse Inventory Search Tool). Like WIST, it provides access to a complete data record of all MODIS and ASTER products available from the LP DAAC.
However, it is much easier and faster to use then WIST or any of the other data search and retrieval tools. You can select the data in a few simple steps, after which you are presented by a download link. That will give you a pop-up explaining that you will be downloading a text file with download links and the best way to use this text files to download the files (for Linux they suggest wget or cURL, see screen-shot of pop-up below).
Pretty cool way I think. It makes downloading extremely easy and flexible. I am downloading some data right now.. when done, let’s see how difficult (or easy, let’s be optimistic) it is to import the data in my GRASS GIS database. On the GRASS GIS wiki (go there) several methods are outlined, the easiest probably being the method 1 (using the gdal tool).
Update: I went for the easier solution; the MODIS Reprojection Tool from the same people making the MODIS data available, USGA LP DAAC. It converts, reprojects and mosaics your data tiles in a few very simple steps. Check out their manual.