A piece of software that has a lot of functionality but is not for the timid user. A person with a power tool can do a lot of damage unless they know what they're doing: this applies to software tools as much as to the sort with rotating sharp bits.

"Power tools" may appeal to "PowerUsers".

* UnixPowerTools: http://www.oreilly.com/catalog/upt2/
* PerlPowerTools: http://www.perl.com/pub/language/ppt/

(Hmm. Maybe a "perl power tool" is a motorized SwissArmyKnife. ''Actually, Perl itself is sometimes referred to as a "Swiss army chainsaw" -- see http://www.catb.org/jargon/html/S/Swiss-Army-chainsaw.html.'')