I have similar requirements, although my initial voltage will either be 5 or 12 V. The required output voltages are 1.8 and 2.8 V. I had ordered a set of samples of LM22674 (http://www.national.com/ds/LM/LM22674.pdf) and LM22675 (http://www.national.com/ds/LM/LM22675.pdf) step down switches, but have realised that they are probably overkill for my project. As stated above, they're buck regulators, with ~ 90% efficiency with input voltage of 5 V (4.6 V min). Obviously, that's too high for your project, but I'm sure you can find equivalents.
As an aside, does anyone have any suggestions as to what the best way to step down 5 or 12 V to 1.8 and 2.8 V is? The switchers mentioned above are 500 mA and 1 A capable, and my project requires ~ 10 mA max. Thank you!