For collections and bookmarks from desktop
I'd especially like to see the ability for Pro Subscribers to upload their own Icons in .png format. SVG support would be swell, but IMHO custom icon upload is something that would add tremendous value to an already fantastic software product.
You can already do this. Just put the image you want as the icon in a free (or paid) dropbox account, copy the public link to it, and then change the zero at the end of the link to a 1 (dl=1). Then link to the image, via your newly created url, to whichever Raindrop bookmark(s) you want :)