I use this mods :
Balkons Weapon mod - a cool mod wich adds some new weapons to minecraft
TooManyItems - I think all of you know this one
SDKs Gunmod - adds guns and grenades , also war-equipment
Thx HeloMod - I got this one just for testing it
ZeppelinMod - With this one you can build Warships and stuff
Flans Mods - This Mods are for the pure awesomeness
The Explosive+ mod - This mod adds some interesting new Explosives (like said in the name)
And last but not least AncientWarfare mod - this mod adds soldiers and anient war machines (its like flans mod like 1000 years ago)
maybe you should check out one of these mods because they are all cool and helpfull for your minecraft
Industrial Craft 2 - technic mod that adds electricity, new ores tools and even nuclear reactor
Red Power 2 - 1) adds new structures to the world
2) adds new ores and tools
3) adds bluetricity to the game
BuildCraft - adds item/liquid pipes, auto workbench and many many more
Custom NPC - this mod allows you to create custom Npc's and give them weapons/tools/armor and set their job like Trader, Item giver, Mercenary etc.
TrainCraft - adds trains to the game
Computer Craft - adds programmable computers to the game that has Lua OS
Jammy Furniture mod - adds a lot of decorations blocks like sofas, armchairs etc.
Rei's Minimap - adds minimap to the game
MineChem - adds chemistry to the game
Pam's WeeeFlowers - adds many flowers
RailCraft - adds new type of tracks (rails)
Forestry - adds bees, new type of woods, autofarms of any type of plants
Shutter Doors - no comments...
ThaumCraft - adds some mystic and magic to the game
MystCraft - adds infinite count of new dimensions
Mo' Foods and Crops - adds new foods
Mo' Creatures - new animals, fish and hostile mobs
Portal gun - adds some elements from Portal game
Ancient Warfare - adds some ancient vehicles like hawcha, catapult etc.
Multipage chest - adds only one chest that can keep about 500 stacks of anything
Not Enough Items - like Too Many Items. Also has enchantment and recipe function
DamageIndicator - cool mod that will show health of mobs/other players.
Fossil and Archeology - adds some fossils and living dinosaurs, sabrewoves and mamonts.
ICBM - awesome mod that adds a lot of explosives, grenades and Intercontinetal Ballisstic Missiles. (Requires Universal Electricity mod)