As well as the obvious things such as a cutting mat and acrylic rulers, my list of essentials includes:

Size 11 sharps
Size 11 big-eye betweens
Short, fine pins for most of my piecing
A variety of pins and needles for other purposes
A ball of tatting thread, size 7 embroidery needs, big safety pins, masking tape and a 1m aluminium ruler for basting
Paperweights come in surprisingly useful now and again
Freezer paper, sharpie markers and a set of wax-based pencils for non-geometric piecing or appliqué
Graph paper
Travel iron and tabletop ironing board
Little tupperware containers to hold the quilting (as opposed to piecing) supplies for one quilt or to use as a bin
Aunt Becky protector for the under finger
A variety of marking pencils and pens
Template plastic and craft knife

And this wasn't meant to be an exhaustive list, so I'll stop now!