I've had space constraints for some time. I found that nearly all the under-shelving, bookcase-sides, and under-desk flat spaces were virtually clutter-free. So I went to local bigbox store and got a 6' x 3" strip of adhesive backed velcro [walmart in the arts & crafts section]. I put about 2" - 4" velcro strips [larger pieces on heavier items] on things like power strips, batt backups, USB multi-port, router, cable modem, surge protectors, and external backup-in-a-box, etc, etc, etc and stuck them under desk surfaces, under book shelves and on bookcase sides.
The cables are still everywhere connecting the various now mounted-out-of-the-way gizmos, but they will soon join the velcro'd gang's relative locations.