Wizards of the Coast provides free Star Wars Miniatures scenarios to their website, to which I am a regular contributor. Below is an index to the scenarios, which will be updated periodically.

For those new to Star Wars Miniatures, a scenario (also called a mission) is a set-piece skirmish. Whereas in a typical game the players build and field squads of their own creation, a scenario defines makeup of each squad plus the map set-up. The scenario also details the victory conditions, which may be something other than simply defeating the opposing squad. To that end, the scenario may also include a number of special rules not used in a regular skirmish.

Think of a scenario as a single movie scene or, if you are familiar with RPGs, a single encounter. Some scenarios re-create specific movie or EU scenes, others are "what-if" siutations. If you are interested in re-playing the movies and Clone Wars series, take a look at the Ultimate Missions books.

The index below is by author, then in order of release (most recent first). The associated set is also listed for each entry:
RS=Rebel Storm
CS=Clone Strtike
RotS=Revenge of the Sith
Univ=Universe
AoE=Attack on Endor
CotF=Champions of the Force
BH=Bounty Hunters
AE=Alliance and Empire
TFU=The Force Unleashed
SB=Starship Battles
If the scenario uses a map from an Ultimate Missions book, that is also noted (UM:RS, UM:CS, UM:RotS.).

My Scenarios:
Detention Breakout (AE, RS, CS, AoE, U, AoE map)
Insertion Point (SB)
Unfinished Business: Part 1 (SB), Part 2 (RS, CS, CotF, BH, UM:RotS map), Part 3 (RS, CotF, BH, AoE map)
Rivals (BH, AoE map)
Rebel Raiders (SB)
Knights of the Old Republic: Opportunities: Part 1 (CotF, RotS map); Part 2 (CotF, Univ., RotS, RS, AoE map); Part 3 (CotF, Univ.,RS, AoE map); RPG article.
The Yuuzhan Vong Advance (Univ., CS starter map)
Black Sun Nexu (Univ, UM:CS, CS)
A Warlord's Fury (RS, CS, RotS, Univ, AoE);
Ewok Ambush (RS, AoE);
Jabba's Rancor: Part 1 (RS, CS, Univ); Part 2 (RS, RotS, Univ); Part 3 (RS, Univ);
Tusken Rustlers (Univ, RotS)
Vader's Pursuit (RotS)
Execute Order 66 (RotS)
Repel Boarders (RotS): Part 1, Part 2
Hired Guns (CS, UM: CS)
Droidworks Assault (CS): Part 1, Part 2, Part 3
Talnar's Tatooine Tratior (RS, UM:RS)
Han Solo vs. the Death Star (RS)
Raiding Sunfire Outpost (RS)

Jason Tanner
Peril in the Kailion Caves (CotF, RotS, CS, AE, U, AoE Map)

Abel G. Peņa and Jason Fry
Kyle Katarn's Tale (RS): Part 1, Part 2, Part 3, Part 4, Part 5
See Abel G. Peņa's blog comments on this series here.

Jason Fry
The Hunt Within (RS, UM: RS): Part 1, Part 2, Part 3, Part 4, Parts 5 & 6

Tim Bresnan
Two Jedi Walk into a Bar (CS, UM: CS)
Maul Madness (CS, UM: CS)
Mini-Mimban (RS, UM: RS)

Jason Cagle
Father's Heir (RS) (includes 2 downloadable terrain tiles)
Stealing the Shuttle (RS)
Sore Loser's Revenge (RS)

Erik A. Dewey
Cantina Raid (RS, UM: RS)

Unknown / Wizards of the Coast staff
Into the Garbage Chute, Flyboy (RS)
Who Shoots First? (RS, UM: RS)
The Theft of Vader's Helmet (RS)
Holiday Tiles (Downloadable terrain tiles of desert and the Sarlacc)

Updated 12/30/07