Every week our plan is to ride a different subway line, or goto a public park & spend a few hours assaulting the personal space of unassuming travelers in an effort to sketch them. Bring your pens, pencils, charcoal & sketchbooks. Feel free to see some work (http://www.conceptart.org/forums/showthread.php?t=40514) from past group meets displayed on the ConceptArt.org forum.
Drawing on the subway especially presents a great opportunity to observe people. Also, by not providing you with a lot of time or still poses it forces you to get down the essential gesture of a person. I've been told & read that many learning artists have used this strategy to improve & develop their life drawing skills. George Pratt (Enemy Ace, Wolverine: Netsuke), credits this method for his development as well. He would spend hours on the subway to & from Pratt Institute in the late 70's sketching people. As such, we welcome every skill level, from beginners up.
If you're looking for a sketchgroup in your area, try this listing (http://www.cgtalk.com/showthread.php?t=247487) and see what you get.