The D&D 3.5 core rules do not specify which weapons can be used for sneak attack. The Rogue class is inherently proficient in Simple Weapons, thus it may be surmised that as long as Simple Weapons are used in combat a Rogue may perform a Sneak Attack. Our house rules specify exactly which types of weapons may be used for a Sneak Attack.
Ranged
A Sneak Attack may not be made using a ranged weapon under any condition. Melee weapons with ranged rules, such as daggers, still carry the potential of delivering a Sneak Attack as long as they are executed in melee. To clarify, a Rogue may make a Sneak Attack using a dagger with melee rules but may not Sneak Attack by throwing the dagger.
Melee
A Rogue may not make a Sneak Attack using medium or large weapons. The weapon must be classified as SMALL, preferably a piercing weapon. Slashing weapons absolutely may not be used to make a Sneak Attack. Small, bludgeoning weapons such as the Light Mace may be acceptable because they are swung easily.
Explanation
In combat a Sneak Attack is the process of exploiting an opening provided by an opponent by placing a quick and well-executed hit to that vulnerable spot. This attack may only be made in melee because you are right there next to your opponent and can make a decision and react quicker than if you were at a distance. Ranged attacks take a little more time to execute than melee attacks because they require more precision. Whether throwing a dagger or loosing an arrow, launching a ranged missile requires at least one more step: aim. Although this step is not reflected at the table, the reality is even a split second extra to aim can cost you the opening. Therefore, Sneak Attacks may not be executed outside of melee.