> "online learning" ... and the subject is unfortunately un-googleable

That's not a surprise; "online learning" is a pretty misleading name. Here are some better alternatives:

  * incremental learning / training
  * stream-based learning / training

So, let's use these terms instead -- then it will be easier to find in your favorite search engine.

Here is one example using the term "stream-based learning":

http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1.79...