I'm planning on fiddling around with Deathwatch in a way similar to what I did with Dark Heresy, and figure that the part of Deathwatch that's most important is the combat. Since playtesting will probably be individual fights, I need some awesome ideas. Other people could probably benefit from this as well.

I've got one to start us off:

The Flying Menace: In the midst of a late-phase Tyranid invasion, a Harridan creature circles the battlefield from above, serving as a transport for hordes of Gargoyles and obliterating allied armour with it's acidic bio-cannons. The kill-team must drop onto the massive creature's back and attack various weak points while fighting off Gargoyles. Once the beast is dead, the kill-team will freefall to the planet's surface to begin the mission proper.

One that I was planning, but never got around to doing was the following situation:

Players are investigating a strange psy-signature eminating from a dormant, drifting Tyranid bioship.  As the kill-team boards, they lose contact with their ship, but most would chalk it up to interferance from inside the bioship.  While investigating they start to notice the bioship is coming back to life and spawning Tyranids to fight them - simple creatures at first but as the ship begins to reawaken, more advanced life forms start to appear.

Continuing through the tyranid bloodshed, the Kill-Team meet Eldar who are fighting for the same goal.  The Kill Team must face a choice: ally with the Eldar and fight the Tyranids until the objective is achieved, then attempt to betray the Eldar before being betrayed themselves or fight the Eldar and face foes on both sides.

In my game, I planned the psy-source to be an Eldar Soulwell that was being fed upon by a powerful Zoanthrope.

Plushy said:

Don't you mean "Imperial armour"?

The kill team, whilst travesing through a dense forrest , come across a broken down chimira with bodies splattered all over the place… as they aproach they see that one of the men is still (barely) alive, choking up blood and the like… if they try and set him free it turns out to be a trap with , rigged to explode on contact , grenades , and hence the ambush is sprung and a team of (insert race and units here) jumps from cover to engage the team whilst disoriantated from the grenades…

The great thing about Death Watch, is that they are about the right power level to fight just about anything from the Warhammer 40k table top game.  This is not true for for DH or even RT. 

Despite the fact that Space Marines are genetically engineered super humans with ancient and powerful equipment, there are about average for troop types in the table top game.

So just bring up teh games workshop site or just about any other site talking about the 40K universe and pick something.  Chances are it will be a good fight for a DW kill team.

Eldar - check

Dark Eldar - check

Tau - check

Tyranids - check

Orks - check

Necrons - check

Daemons - check

Chaos Marines - check

And in the darkness of the far future there is plenty of Imperial on Imperial action so you can add Imperial Guard, Sisters of Battle, and Space Marines to that list as well, especially when the inquisition gets involved

In other words if it exsists in the 40k space marines fight it.