Tool environment plugin lets you use "tools" in unusual ways, such as from shell scripts.
See JENKINS-4532 for motivation.
Some screenshots are better than a long discussion:
Compared to Custom Tools Plugin the advantage is that you can use the tool in arbitrary ways, not just running an executable from it.
See GitHub Release for more recent versions.
1.1 released Mar 27 2013
1.0 released Feb 15 2010