SC2Mapster

Bubbles' Tower Defense

Puzzle TD

Sheep Tag based game.

Turret Defense Map for 1 or 2 players

3v3v3v3 Base building map and more! Similar to Castle Fight, Nexus Wars.

Wintermaul by STRiDEX

Cannon Defense

Basic Idea from Power Towers in WC3 with many changes

A great starting point for someone interested in making a Squadron TD genre game.

Missile Command

Basic arena. Each player spawns units automatically and can buy more buildings for other units and upgrades.

Grass TD

HALO [ultimate tug of war]

MindBreaker TD

Desert Tower Defense - 20 Waves - 5 Tower Types - 11 Players (Beta)

A TD where turrets and creep level up and creeps use random abilities

Unit defense. Build a variety of units to decimate the enemy waves.

Defend against wave after wave of zerg forces with unique Protoss towers.

ShadowTD

HOLD-THE-LINE