Corporate goliath McDonald's is at it again.

After successfully launching a two-week "free coffee" campaign across Canada in 2009, McDonald's will be repeating the promotion this year.

And yes, the offer is exactly what it sounds like. For two weeks, from March 1-14, Canadians can again head into their local McDonald's for a free small coffee. (Online reports have noted that larger sizes may be made available to customers at lower-volume locations).

That's it. No further purchase or commitment required. Just walk into or drive through any McDonald's and order your free coffee. Talk about an effective way to get customers in the door.

The promotion operates around the principle that it takes people about two weeks to form a new habit. If people get into the routine of heading to their local McDonald's for a free coffee every day for two weeks, in theory, they'll keep coming back (and paying for their coffee) once the promotion is over.

It's an interesting — and somewhat daring — marketing strategy, particularly in the midst of still-lagging economic times that have seen Canadian coffee competitors Tim Hortons and Starbucks struggling more than usual just to maintain their market share.

So while there may be no such thing as a free lunch, the free coffee will definitely be up for grabs soon — but only for a limited time. Mark your calendars.