Are there any mods available for OFP?

Not yet but there are a number of them being planned and designed and some have them are beginning to start releasing weapons, vehicles and soldier skins addon. Among them are:

Der Bundeswehr (German Army) Mod

Operation White Night

BattleWAR

The Chain of Command

The WWII Team

Contested Ground and Unhallowed Ground

CrimeCity

Invasion 1944: The Field of Glory

Project: Stargate

The Lost Brothers

Planet of War

Crisis Kosovo

Blackhawk Down

DDAM: Danish Army Mod

Winter March

G8: Urban War Mod

Men at Arms - Hired Soldiers

The Falklands Mod

Iron Wolf

Did I miss any? Something listed here bite the dust? Just let me know, OK?