4 Levels. Really, really well thought out. These would be really tough as net levels (unless you turned aliens off), but for practice, you won't find a better set. (In fact, these benefit from the Canyonlands textureset, but don't require it. )

Modified Waldo World

Two maps. These are maps of an office building, one with the ability to go outside. Bizarre texture choices, and skimpy weapons for net play, but a pretty good flow, nonetheless.

A central pillar and four outside rooms. All the good ammo's on the pillar, but you're such an easy target...