Wi-Fi Toolkit Suggestions?

I work for a large corporation, and so have little need or use for a
dedicated wireless toolkit. Sure, I use most wireless tools on an
regular basis, but have nothing packed into a toolkit. By toolkit, I'm
speaking about a grab-bag of essential Wi-Fi tools, software, and
accessories that consultants and contractors have packed at all times,
ready to pickup and go on an assignment at a moments notice without
foreknowledge of the situation they're being called into.

I've started a list, but would like tips from engineers using such a
toolkit in their everyday routine.

Please post your favorite items in the comments section. I'll post my
compiled list once finalized.