Here is my Skaven Warband Roster (in a zip file).
Explanation: This is my Skaven Swarm.
I have 5 heroes with minimal equipment and no armor. My Assassin Adept (Leader) has fighting claws because those claws are awesome. Besides that, every other hero has either a sword and dagger or spear and dagger. (They both cost 10g. The sword gives you a possible save to hit and the spear gives you the first hit when someone charges you.)
For henchmen, I got 1 Vermikin with a club and dagger, and the rest of the gold crowns (180) went to get 12 Giant Rats. Nothing like starting the game with 18 models while most warbands start with 6-8. This swarm with some cheap ganging tactics ends up with 3 or 4 instances of 4 vs 1, and the other team instantly has to take a route test.
Long live the Swarm!