based off of

[Ether]

Random observation: I see the phrase "based off of" a lot in these forums.

I never encounter it anywhere else.

[Tristan Lall]

I never encounter it anywhere else.
122 million hits and getting more popular (http://books.google.com/ngrams/graph?content=based+off+of&year_start=1975&year_end=2013&corpus=17&smoothing=3&share=), according to Google.

[Andrew Lawrence]

Based off of this statement, I concede that we use the phrase "based off of" quite frequently.