At least $10 in royalties (see Box 2 on page 4) or broker payments in lieu of dividends or tax-exempt interest (see Box 8 on page 7);
At least $600 in rents, services (including parts and materials), prizes and awards, other income payments, medical and health care payments, crop insurance proceeds, cash payments for fish (or other aquatic life) you purchase from anyone engaged in the trade or business of catching fish, or, generally, the cash paid from a notional principal contract to an individual, partnership, or estate;
Any fishing boat proceeds; or
Gross proceeds of $600 or more paid to an attorney. See Payments to attorneys on page 2."
Here is a great link to a calendar that shows various tax deadlines for 2011: IRS Tax Calender. You might want to bookmark it so you have it at your finger tips.
Also for those who only have a few 1099-misc forms or W-2's to file , you can file them for free at