Guessed & Guest

Guest – Knock, knock.
Guessed – Who's there?

Some & Sum

As in, "You need to add some to get sum."

Catch up & Ketchup

Don't get me started on "catsup."

All & Awl

As in "There are many different types of awls, but they all do the same thing as a sharp stick."

Missed & Mist

Is it just me, or is this blog full of people who are really bad at sports?

Vice & Vise

With a C – a habit deemed inappropriate or immoral, often used to describe gambling, drinking, or sexual depravity (or as I like to call it: Tuesday).
With an S – a clamping tool used to hold an object still while it is worked upon.

Ail & Ale

Sunday morning's ode to Saturday night.