Here's an interesting site for us language fans (and pedants):

Eggcorns

What examples do you have which irritate or amuse? 'Mute point' for 'moot point' is the one that irritates me. Children, of course, invent their own through the same process of substituting the known for the unknown or misunderstood. (My mother as a child was convinced of the existence of elephants in the West. Why? Well,does the song 'Home on the Range' not go:

'Home, home on the range
Where the dear little elephants play' ? )

Oh, I can think of a number:

Using "of" as an auxiliary verb
There should of been less homework.

Doggy-dog world
For all intensive purposes

And the famous hymn
Gladly, the cross-eyed bear.

Or from the Neil Diamond song "For Reverend Bluejeans"