Straight Single Pointed Knitting needles
Multiple sizes and lengths of circular knitting needles.
Double Pointed Knitting Needles
Stitch Markers are really helpful when working patterns like basketweave where there is a common set pattern.
Cable needles (rosewood are so nice)
Stitch holders (useful when knitting sleeves on a sweater)
Row counter app on Iphone
Manual row counter (great because you don't have to worry about batteries)
Needle holders are wrapped around the two needles so that you don't lose stitches when you aren't working on project.
Tool pouch and scissors