Making Logos

What program can I use a Mac to create logos?

I make logos for subdivisions of a real estate site and I was wondering what programs of Windows or Mac be good for the manufacture of these logos, preferably free or not too expensive!

You can try these: http://www.inkscape.org/ or http://www.tweakersoft.com/vectordesigner/

Photoshop CS5: Elliptical Logo Making / Creating – Tutorial