I have always wanted a Roman mod for Warband, so I made one myself. What happens is the Romans invade Caladria.. oh just read the story!

The Story
The Romans have come seeking new lands, and have completely taken over the Swadians.
And the Gauls, having lost all their lands to the Romans, came and took over the Nords.
Now the Rhodoks, Veagirs, Khergits and Sarranids realize that the Romans and Gauls pose
a threat to their kingdoms. You arrive in Caladria, with a huge war going on.

So now, you only have four options:
1. Join the Romans, and help them take over Caladria
2. Join the Gauls, and help them take over Caladria
3. Make your own faction and destroy everybody else
-------------------- OR ---------------------------
4. Join one of the other factions to help destroy the Romans and Gauls.

Some of the Basic Features:

2 new factions, The Roman Empire and the Gauls
The new factions have new troops and troop trees
New Roman/Gallic items - Special Thanks to Llew2
The Lords of Rome/Gaul have new names
The Romans & Gauls Towns, Castles and Villages are renamed

And Some Tweaks:

Larger party size
Bandits have larger party sizes, minimum 15, max 50 with looters having a max of 100.
Higher bet options for tournaments
Cattle follow you
Minimum of 5 recruits per village, maximum 20
Siege tower moving speed cut in half
Building improvements cut down by half
Some dialogs changed.
And some other stuff, that I can't remember

More features to come in future releases!

The team:
KingLuke (Me)
Marcus Fulvius Optimus (Historical Information)
Lord Archaon (Graphics)
Guacharo (Graphics)

Credits:
Llew2 - For his Roman/Gallic Items and Textures
The people that posted below- For Giving me some historical information
Lord Archaon - For the wonderful signature!
Queen Pinky - For another awesome signature!
Guacharo - For another cool signature!

Screenshots & More Information here: http://forums.taleworlds.com/index.php/topic,140915.0.html

Changelog:
1.3 - New Menu and Loading screen, Romes & Gauls troop trees revamped.
1.2 - Makes Roman/Gallic Items more Available, Fixed Julius Caesar, and Tavern Keepers Buy Prisoners.
1.1 - Senuzgda Castle and Nomar renamed, some tweaks fixed.