http://mahout.apache.org

http://machinelearning.reddit.com

http://mloss.org

http://jmlr.csail.mit.edu/

http://shop.oreilly.com/product/9780596529321.do

http://www.amazon.com/Algorithms-Intelligent-Web-Haralambos-...

http://www.amazon.com/Mahout-Action-Sean-Owen/dp/1935182684/...

http://www.amazon.com/Collective-Intelligence-Action-Satnam-...

http://www.amazon.com/Machine-Learning-Hackers-Drew-Conway/d...

http://www.amazon.com/Machine-Learning-Action-Peter-Harringt...

http://www.metaoptimize.com/qa

http://stats.stackexchange.com

You can't take enough maths and statistics classes. Machine Learning - these days at least - is very maths and statistics oriented. Linear Algebra is big, so make sure you have that covered.

If you want to get your toes in the water a bit with ML, there are some great ML libraries that encapsulate some of the popular algorithms. Mahout[1], Weka[2] and Mallet[3] are popular in the Java world,

A lot of folks use Python for ML as well, and there are some good libraries there.

The R language is also popular in ML circles; as is C++. If you learn some combination of Java, Python, C++ and/or R, you'll be in good shape from a programming language standpoint.

Check out http://mloss.org/software/ also.

Some good books to get started with include:

Algorithms of the Intelligent Web[4]

Programming Collective Intelligence[5]

Collective Intelligence In Action[6]

Stanford make a great series of lectures[7] available online that you might find useful.

[1]: http://mahout.apache.org/

[2]: http://www.cs.waikato.ac.nz/ml/weka/

[3]: http://mallet.cs.umass.edu/

[4]: http://www.manning.com/marmanis/

[5]: http://www.amazon.com/gp/product/0596529325

[6]: http://www.amazon.com/Collective-Intelligence-Action-Satnam-...

[7]: http://see.stanford.edu/see/lecturelist.aspx?coll=348ca38a-3...

http://www.amazon.com/Collective-Intelligence-Action-Satnam-...

http://www.amazon.com/Algorithms-Intelligent-Web-Haralambos-...

There's really good books on Data Mining at Borders, and a recent bunch of "collective intelligence" books; the Manning books are excellent, but you have know java; you probably also want to install Weka and R, look at the Python suite (numpy, scipy, matplotlib), tools like that; also look up the ~107 (!) algorithms that Bellkor used for Netflix comp.

http://www.research.att.com/~volinsky/netflix/

http://www.amazon.com/Programming-Collective-Intelligence-Bu...

http://www.amazon.com/Collective-Intelligence-Action-Satnam-...

http://www.amazon.com/Algorithms-Intelligent-Web-Haralambos-...