Grammar Police: This is Just Too Much!

Two/Too/To
These words are so basic that I think anyone who uses them incorrectly needs to go back to first grade spelling class, or at least proofread more carefully. I've seen this error made so often on AC that if it continues I'm going to start making arrests!

Two, of course, refers to the number that comes after one! This word is seldom mistaken for to or too.
Too means in addition to, also, or excessively.
To is for all other uses.

Examples:
This chili is too spicy for my taste. (The chili is excessively spicy.)
Are you going to the dance, too? (We're going to the dance. Are you going also?)
I broke my leg skiing when I ran into a tree, and bumped my head, too. (In addition to my broken leg, I have a headache!)

The last example brings up another common grammar mistake:

Into/In to
Into is a preposition that asks the question "where?" or "what?"
Examples:
When I blew a tire, my car went into the lake.
My son went into the army.
My dog turns into a snarling beast when strangers approach.

Into can also relate to time:
My flowers kept blooming into autumn.

In math class, into refers to division:
Two goes into ten five times.

In to are separate words that are sometimes used next to one another to imply intent.
Examples:
The firemen rushed in to rescue the family from their burning house.
I was near the video store, so I went in to rent a movie.

If you're unsure whether in to or into is correct, read the sentence aloud, pausing between in and to. If it sounds awkward, into is probably correct.