I have a five (almost 6) year old boy who's very chatty and outgoing.
I was considering channeling some of that energy toward acting. I'm
not planning on making this a career for either one of us, mabe a
couple of commercials. We live in the Chicagoland area. My question
is; Is there such a thing as open auditions for child actors close to
where we live? I really don't want to go through the whole "portfolio"
thing. I do have some nice photos of him (I'm a photographer) whould
that be enough for an audition? Basically I want to know if he's got
what it takes, and the least painful way to go about it. If we need an
agent, how do we get the one with the highest success rate? I know I'm
probably expecting too much, but I hope someone can help. Thanks.

In my personal opinion as a former union actress, I would channel his
energy into live theatre. He's more likely to be cast, and it will
take more time, energy, and focus on his part. You might start by
finding a youth theatre camp for him this summer, or any children's
theatre group. If he likes it, he can start auditioning for community
theatre productions. And if he really likes it, maybe he'll go pro :)

Kriswrite

Try the agency mentioned in this article.  

http://www.findarticles.com/cf_dls/m0DUO/26_40/55427436/p1/article.jhtml

Thank you both for your comments, I will look into it.

You might also check around for scheduled movie shoots that are
seeking extras. Let the child do this a few times and see if he likes
it, or better yet, if someone notices "him". Search for "movie extras"
to find opportunities near you. These aren't normally paying positions
but the experience is great and occassionally movie extras are even
chosen for speaking roles. I did it myself a couple of times just for
the fun of it and some time back, only my second time mind you, I was
actually cast as a credited character in a movie (that is still in
production) and given a brief speaking role.

Regards;
tutuzdad-ga