I had similar needs and found that klibc fit it quite well. The only downside (for commercial use) is that the distribution includes a few GPL-licensed files, even though most of it is BSD-licensed. I have hacked a minimal version of it here.
This is even more limited than PDCLib, and suitable if you just need a few basic functions such as printf and strtok. Compiles to just 4kB with all functions included.
