I have the following gadgets that I love and use most of the time:
Martelli Binder--I bind most of my quilts with it
Seam ripper identical to the one that came with my sewing machine- I keep extras around so I can replace when they get dull.--also use them as stilettos
60mm rotary cutter and starch for gluing layers of fabric together (really helps when cutting multiples--can cut through about 8 layers of fabric)
Large cutting mat - 55" x 32"--great for pin basting large quilts not to mention cutting big pieces of fabric
Westalee ruler foot for FMQing with rulers on my domestic machine--love it
16" square ruler and 12" x 24" ruler--great for squaring up a quilt before binding, or for squaring up blocks before joining
The FMQ foot that came with my PQ1500s-- better visibility than any FMQ foot I've used on my other machines
Gadgets that I love having, but don't always use:
Big Shot Pro and sizzix and accuquilt dies--I really like this for when I'm making a quilt that has lots of really small pieces
Add a quarter ruler-- for paper piecing
I'm sure there are others LOL
Rob