We report on our latest improvements in organic field-effect transistors (OFETs) using ultra-thin anodized gate insulators. Anodization of titanium (Ti) is an extremely cheap and simple technique to obtain high-quality, very thin (similar to 75 nm), pinhole-free and robust gate insulators for OFETs. The anodized insulators have been tested in transistors using pentacene and poly(triarylamine) (PTAA) as active layers. The fabricated devices display low-threshold, normally "off" OFETs with negligible hysteresis, good carrier mobility, high gate capacitance, and exceptionally low inverse subthreshold. slope. Device performance is improved via chemical modification of TiO2 with an octadecyltrichlorosilane (OTS) self-assembled monolayer (SAM). As the result of this combination of favorable properties, we have demonstrated OFETs that can be operated with voltages well below 1 V.