Why don't you contribute to Apache Hadoop/Mahout by helping them implement additional algorithms?
https://cwiki.apache.org/confluence/display/MAHOUT/Algorithms
Has a number of algorithms marked as "open". To my understanding, they could use help with implementing these? And there are hundreds of algorithms even missing from this list.
By any means, since you want to do something with Hadoop, why don't you ask them what they need instead of asking on some random internet site?
