The hyper-expensive and [sometimes-maligned][maligned] Unreal Engine [gets a free / indie version][link]. [The Unreal Development Kit][link] is free for non-commercial use, and $2500 per-seat for commercial games.
[With Unity making a similar offering][unity] last week, the independent games scene is only going to get better.
[link]: http://www.udk.com/index.html “UDK – Unreal Development Kit – Epic Games”
[unity]: http://extrafuture.com/2009/10/28/game-engine-unity-launches-free-option/ “Unity Launches Free Option”
[maligned]: http://en.wikipedia.org/wiki/Too_Human#Unreal_Engine_dispute “Epic Games .vs. Silicon Knights”