Note: This version is no longer maintained. The mod has been re-written for 1.8.9 and 1.9. You can find the project page here!
This mod adds lasers to Minecraft.
This mod is built as an add-on to Thermal Expansion, so it is recommended that you play with TE (and its dependancies!) also installed. Any mod that uses the RedstoneFlux API, and can somehow get that RF into an item (such as EnderIO or Mekanism) will also work. (Note that if you do take this route, Thermal Foundation is still required)
zzApotheosis has done a mod spotlight for version 0.5. It covers the basics of the mod, and the information is still mostly correct. Come check it out!
I did my own spotlight for version 0.8. It skims over the basics, and covers the more complex things.
More details are on the wiki! It's still being written, so check back every now and then. The basics are there already, so you should be able to get started!
Feel free to use the mod in a modpack. You don't need to ask, but it would be nice to let me know :)