Tukcherry Double-Sided Self-Healing Cutting/Desk Mat
A self-healing cutting mat like this one is ostensibly meant for doing crafts and sewing, etc. on, but IMO it's just as good to use as a cool-looking desk mat. It's perhaps more grippy than the surface of your otherwise nice desk, so the stuff you set down on it won't go slipping around. The grid and designs on it can also act as guidelines for keeping your workspace stuff organized, if you're like me and can be a bit crazy about that.
I also dig that the designs have a sort of retro-futuristic space system vibe to them, like a HUD you'd see in some old sci-fi movie ???
You can get the A4 (12" x 9") size for $12 on Amazon.