Matt Pliszka reviewedPure Chat - Free Live ChatFree full-featured live chat with unlimited users & chats
 Recommended
Pros: 

free version, visitors' monitoring/overview, quite easy to use, many customization options

Cons: 

quite basic reporting/analytics

Really like it for the way it lets you monitor who is currently browsing your website and what pages they're looking at.

Matt Pliszka has used this product for one month.