Here are some networking resources and tools I've found useful:
- VisualLand - a combination network simulator, Animated howto, tutorial, general-info site
- 9tut - a cisco certification oriented site with practice test resources
- RouteMyWorld - a ccna/ccnp blog
- PacketLife - a general network engineering blog
- IP Calculator - a subnet calculator
- CentralOps - a general purpose DNS/Traceroute/ServiceScannet/Whois utility site
- The Net - CCIE blog with GNS3 labs
- All About Networking - blog with cisco lab links and gns3 labs
- Free CCNA WorkBook - CCNA exam prep materials
- PCAPR - Online Packet Captures + social networking.
