Many services (eg, bit.ly) will shorten URLs, even those w/ GET data, since that's just part of the URL.
Do any work w/ POST data? In some cases (eg, certain types of CBOE option quotes), you must POST data to get the information you want.
The service might bring up a page (eg, shorten.com/foo) that has:
<form action="/url/to/post/to">
<input type="hidden" name="var1" value="val1">
...
<input type="submit" value="SUBMIT">
</form>
where the /url/to/post/to and var1/val1/etc are set by the person creating the shortened URL. It would also say:
"By pressing the button below, you will post this data to this URL: /url/to/post/to: [list of hidden fields and values]"
Seems useful and easy to do... has anyone done it?
OK, this seems to have degenerated into a moral argument. I'll assume the answer is no, no one has already done this.