I have released the first version of Maui, a multi-purpose automatic topic indexing algorithm on both:

• Google Code: maui-indexer.googlecode.com
  
• and Sourceforge: maui-indexer.sourceforge.com.
  

Maui builds on the keyphrase indexing algorithm Kea, but provides additional functionalities:
It allows to assign topics to documents from Wikipedia, by utilizing Dave Milne's tool Wikipedia-Miner.
Maui also has many new features that help identify topics more accurately.