I forgot to include alimony I paid to my ex-wife on last year's return. How do correct this oversight?

To amend your 2006 return file form 1040X for 2006: http://www.irs.gov/pub/irs-pdf/f1040x.pdf

The alimony you paid to your ex=wife is deductible. You will need to amend your 2006 tax return and file Form 1040X.