Hi, you can find some GNS3 labs here : www.ccna-lab.com.
Actually, you don't have to use GNS3, since the web site already launches routers (in dynamips) on its own server.
The web site gives some pdf files with step by step labs and you can do the labs on your own GNS3 or on the site itself.
Here is a snapshot of what it offers.
All the best,
Navid
