1) A CD sleeve with bootable tools like UBCD, UBCD4Win, SeaTools, WinDLG, Ophcrack etc. as well as some blank CDs and DVDs.
2) A spare small capacity USB Key I can use as scratch disk or to make a bootable version of an application I don't have.
3) Paper clip!
4) Velcro Reusable Ties. Similar to Velcro One-Wrap but thinner, lighter, and much much cheaper. 50 of these are about $5 instead of 8 for $5 with the sturdier One-Wraps. Plus, they are small enough to use effectively on things as mundane as charger and USB cables. That reminds me....
5) *EDIT* Ooops, you already had this.
6) A surge protector. The Belkin Home/Office Series is thin & light in a variety of configurations and cable lengths. I try to always have the 6-outlet, 8' Cord with the flat swivel head.