All Intensive Purposes
"All intents and purposes" is a 500-year-old turn of phrase coined in an English Act of Parliament by King Henry VIII. It actually stated, "to all intents, constructions and purposes" and meant "in every practical sense." It was shortened to the popular version in 1709.
The butchered form -- "all intensive purposes" -- sounds similar, which is probably the reason it's been popping up in newspapers and everyday speech since as early as 1870 [sources: Expect Labs, Safire].