I need to find an old tax return, but do not know which company I filed it with. Does anyone know where I might be able to get a copy of it?

Requesting transcripts (individuals):

You have two easy and convenient options for getting copies of your federal tax return information--tax return transcripts and tax account transcripts--by phone or by mail.

Need a Copy of Your Tax Return Information? (http://www.irs.gov/individuals/article/0,,id=110571,00.html)

Read for how to get previous years W2s, 1099s
Your U.S. Tax Return: Missing Forms W-2, 1099-Misc, 1099-Int, 1099-R (http://taxipay.blogspot.com/2008/05/missing-forms-w-2-1099-misc-1099-int.html)