Lots of sewing girls have an Arm Chair Caddy. This is one I made which was a kit by Abbey Lane Quilts called The Abbey Bag and purchased from the lovely girls at Iddy Biddy in QLD.
I was particularly impressed with their idea of adding a circle of Rubberised Shelf Liner to the underside of the pincushion which really does stop it from sliding off the table, chair etc. What a great idea. I hope you like it to!