Mods/Tekkit

Tekkit is a collection of mods available in the Technic Pack from Technic. It is available for both client and server, and additional Bukkit mods can be installed on top of Tekkit.

Included mods
Tekkit 3.1 contains the following mods:

System requirements
Tekkit 3.1.3 currently uses Minecraft 1.4.6 Most likely, you will need to reduce your quality settings to run, otherwise the game will lag immensely, due to all of the various blocks and items added on top of the original game itself.

You must not mind downloading an illegal mod pack. Tekkit's owners keep 100% of the donations, despite this being illegal, and ignoring the mod makers requests.