
These are a few mods that I made after prodding about with some of the data files.
All mods require Grognak's mod manager, which is quite an ingenious way of managing mods.
You can download the mods from here, or from xenolith, in case you want to subscribe only to updates regarding mod changes.

Ion Beam v0.3
This beam was the first proper mod I made for FTL, which hooks into the Federation Cruiser's artillery system, which instead of firing a piercing regular beam, causes ion damage instead. It's very good for disabling systems temporarily, though it is seen to be moderately overpowered.

"Well, this doesn't bode well for the mission." (v0.3)
Download from Dropbox (v0.3) (Includes extra-difficult tutorial, and custom graphics, also for Federation Cruiser)
Video: FTL tutorial gone bad, Ion Beam v0.3
Splint Bombs v0.1
This next mod teleports 5 bombs into the enemy ship where possible, and causes hull breaches when successful. It was here that I learnt that trying to make the artillery system use missiles locks up the system entirely. Still fun to watch the enemy crew try to fix all those breaches, however. Like the Ion Beam, this replaces the default artillery that comes with the Federation Cruiser.
Download from Dropbox (v0.1)
Video: FTL demonstration, Splint Bombs v0.1
Rapid Missiles v0.5
This is a standard weapon mod (so it's very much compatible with the Ion Beam and the Splint Bombs), which simply increases the firing rate of missiles. Does 2 damage per shot, pierces shields, has a 4 second charge time, but requires 4 energy to operate and yes, your missile supply will drop quite quickly.

"Rapid Missiles: Nimble and quick." (v0.1)
Note: as of this version, it currently overrides the first layout of The Kestrel, giving you 12 missiles and the 4 energy needed to operate this piece of machinery. If you're running other weapon mods, be sure to check the mod order.
Rapid Missiles v0.5 - Dropbox
Rapid Missiles v0.1 - Dropbox
Video: FTL demonstration, Rapid Missiles v0.1
Athena Missile Launcher v0.1

The Athena is a missile launcher that doesn't use missiles. Instead, it is built over time, fueled by your reactor. There's nothing too special about this weapon (though the same could be said for a lot of the weapons here), but if you ever find yourself out of missiles and needing to get past a shield, this is a good choice.
Note: this overrides the layout A of The Kestrel, in providing the Athena for you when you begin. Using Rapid Missiles in conjunction? Check your mod order.
Download from Dropbox (v0.1)
Installation for .ftl files
1. Make sure that Grognak's mod manager works properly.
2. Copy the '.ftl' file to the 'mods' directory.
3. Launch the mod manager. You should see the mod you want as one of the options.
4. Select it and click 'OK'.
5. Wait for the unpacking and packing to complete, then launch FTL.
6. Profit!
A note about these weapons
Any mods that replace the artillery system won't work together, so when you're selecting the mods to use, select only ONE of the mods. Any breakage of the game, I hold no responsibility if you haven't installed the mod correctly.
Remember: For any of the above artillery mods, use only ONE AT A TIME.