other than the obvious must have's (main 3d app: max/maya, 2D app: PS, sculpt app: ZB) to do your work... wScite, adblock, xnview, crazybump, nvidia normal map plugins, nDo, filetexturemanager (maya), idlm (take that slow network!), unfold3D
Zbrush, 3dcoat, Silo, UV Layout. These apps continue to allow me to work as far away from max, maya, xsi - whatever the pipeline tool happens to be - until I have to, which is usually only when I need to rig/animate/export.
Deskpins (when I'm stuck on a single monitor setup) Pixeur (sampling colors outside of any app to acquire formulas. great for getting palette ideas off web images without having to save them) WoodWorkshop (mix it with Photoshop and you can get some great tileable wood patterns) all pretty lightweight as well. what's maya…