Hi! I saw this thread started and was curious myself. Here's a
link for the top digital websites for stamping. But don't forget companies who also offer digis and clear stamps, like Power Poppy. I am an Instant Gardener for them, and they have some beautiful images.
Here is another place for more information. And there are lots of sites with free digitals like
DigitalTuesday and
Free Vintage Digi Stamps. Hope this helps and is a start. There are also lots of Pinterest boards for digis. That's a great way to start. But be sure when you use them that they are free or that you purchase them. Enjoy!