Freescale makes some tiny micros which might be useful for very small, inexpensive solutions; ambient sensors, remote devices, smart tags, assist devices.   Way less than fifty cents.  Not very powerful, but small (2x3DFN, six pins).  Limited debug, no ADC, memory paging, no interrupts?  May be wrong about that.

More expensive but much more powerful are the S08QG series, in 8DFN.  No paging needed.  More timers.  There is also a part family in between these, but it apparently is avail in SOIC only.

Here is a comparison guide.  I believe all use the single pin BDM.  Here is a sheet on the debug options for the three device types.  Here is a concise comparison card for the various small package offerings.  Here is a useful comparison between the high end and low end two, which also covers low cost demo boards.  Freescale offers online demo boards (Java driven simulators) and many online microcontroller training courses.