Here is my favorite:

WHY ENGLISH IS SO HARD TO LEARN
We must polish the Polish furniture.
He could lead if he would get the lead out.
The farm was used to produce produce.
The dump was so full that it had to refuse more refuse.
The soldier decided to desert in the desert.
This was a good time to present the present.
A bass was painted on the head of the bass drum.
When shot at, the dove dove into the bushes.
I did not object to the object.
The insurance was invalid for the invalid.
The bandage was wound around the wound.
There was a row among the oarsmen about how to row.
They were too close to the door to close it.
The buck does funny things when the does are present.
They sent a sewer down to stitch the tear in the sewer line.
To help with planting, the farmer taught his sow to sow.
The wind was too strong to wind the sail.
After a number of injections my jaw got number.
Upon seeing the tear in my clothes I shed a tear.
I had to subject the subject to a series of tests.
How can I intimate this to my most intimate friend?
I read it once and will read it again
I learned much from this learned treatise.
I was content to note the content of the message.
The Blessed Virgin blessed her. Blessed her richly.
It’s a bit wicked to over-trim a short wicked candle.
If he will absent himself we mark him absent.
I incline toward bypassing the incline.

Spelling Poems. (via Boing Boing)