Create custom, live-updating tiles (with images!) for Windows 8.1/IE11 users to pin to their Start Screens.
To see the live tiles, you must be running Windows 8.1 and the pinned tiles must be larger than the "small" size (I think they look best with the "Wide" size, which will try to pull in images from your posts). Once you pin a site (or refresh an existing pin by trying to re-pin a site), the live tile should begin working almost immediately. Note that there may be additional delays beyond the settings in the plugin settings page for checking for new posts, due to the multiple levels of feeds needing to update themselves.
Either the image you selected is too small (minimum 310px square) or the filesize of the image you uploaded is too large (maximum 200kb after WordPress converts the image to PNG and resizes it). If the filesize is too large, try a less complicated image (graphics like logos will typically work better than pictures).