... appart of sending them to other sites (for non exclusives) or removing them from the folder "Send to Dreamstime" (or whatever system you use. In my case I have folders, "Send to X").
Some ideas of things I have done:
1. Use them to create a whole new concept: I used a bunch of my refused files to make the "media room" concept (which has sold pretty well!). Not always from these are rejected ones, I used some from the approved ones that fit the concept
Or the four seasons and four elements concepts:
Resubmitting images individually again without correcting the mistakes is forbidden and not tollerated, but the TOS doesn't say anything to use refused images to create a new concept or use them as a part of a new image. Some of those images that are individually rejected for "too many on the site" or "too many of the same series"etc. can be useful together ;)
2. Collages: In spite Dreamstime encourages doing this with similars, some photographers don't like to make this because they think that are giving away too many images in a single sale. In my case, it's a way to take proffit from the refused files in Dreamstime. Some of these images sell individually on other sites, but since they were rejected here, I wanted to make them useful here by making an autum collage (it has sold twice):
3. Retouch the refused image: Sometimes, after an image is rejected, you can redo it and resubmit with a note to the reviewer. This is what I did with my cofee: it was rejected as isolated in black background, so I worked on the background and resubmitted with a note. It was accepted:
4. Make a frame or a background with part of the refused image
I took the ladybug from a rejected image where the ladybug was on a leaf, isolated it and made a "ladybug border", it has sold ;)
I have made also frames isolating flowers or leaves. If you see a pretty element within the rejected image, isolate it and make a new design!
Sometimes you only need a bit of imagination to take advantage of some images. If there's nothing you can do to improve or save them, then just remove from your Dreamstime folder and move on ;)