Cook county recorder does have an online search, but its pretty useless. The information available is minimal. I messed with it for a bit, but didn't see how to get actually addresses or owner information.
There is a phone number, though, so you could just call them and ask if there is some way to search ownership information for (for example) some neighborhood and then get the addresses of the owners.
You may have to go to the recorder's office in person. Sometimes more information is available there than online.
These online systems are ALWAYS obtuse. I've looked at a bunch, and have never seen two that were alike. The information available varies widely, and Cook county looks likes its toward the bottom in terms of data available.
A title company may have more data available. If you're actually closed a transaction with one, try calling them and asking. If not, just start dialing.
Ultimately, you may just have to fork over a few hundred bucks and buy a list.