You can use the Horadric Cube's magical powers to Transmute items into a new item. Place the items into the Cube and hit the Transmute Button. Warning: Any additional items that are not a part of the formula will disappear with a successful Transmutation.

  Place In Cube   Transmutes into   Notes
Diablo II 3 Rings of any type   1 Random Amulet   Usually Produces Junk
Diablo II 3 Amulets   1 Random Ring   Usually Produces Junk
Diablo II 3 Health Potions + 3 Mana Potions   1 Rejuvenation Potion   Use this formula if you are in need of instant healing and/or mana. Any grade of Health/Mana Potion can be used.
Diablo II 3 Health Potions + 3 Mana Potions + 1 Gem (Any Grade)   1 Full Rejuvenation Potion   Use this formula if you are in need of instant full healing and/or mana. Any grade of Health/Mana Potion or Gem can be used.
Diablo II 3 Gems of the Same Type and Grade (lower than Perfect)   1 Higher Grade Gem of the Same Type   Use this formula to upgrade your growing masses of low quality Gems into something more useful.
Diablo II 6 Gems (Any Grade) and 1 Sword   1 Socketed Long Sword   For those that are having trouble finding a socketed weapon. Any One-Handed Sword can be used.
Diablo II 2 Quivers of Arrows   1 Quiver of Bolts   For users of Crossbows that are in need of ammunition. Random quantity of Bolts produced.
Diablo II 2 Quivers of Bolts   1 Quiver of Arrows   For users of Bows that are in need of ammunition. Random quantity of Arrows produced.
Diablo II 1 Spear + 1 Quiver of Arrows   1 Stack of Javelins   Mainly for Amazons that are in need of Javelins to use with skills. Any class/type of Spear can be used.
Diablo II 1 Axe + 2 Daggers   Throwing Axe   Any class/type of Axe can be used (i.e. magic/socketed/non magical axe/etc). Random quantity of throwing axes produced.
Diablo II 1 Ring + 1 Emerald + 4 Antidote Potions   1 Viridian Ring   Use this formula to create a Poison Resistance Ring. Any grade of Emerald can be used. The Viridian Ring has a random percentage of Poison Resistance
Diablo II 1 Ring + 1 Ruby + 4 Exploding Potions   1 Garnet Ring   Use this formula to create a Fire Resistance Ring. Any grade of Ruby can be used. The Garnet Ring has a random percentage of Fire Resistance
Diablo II 1 Ring + 1 Sapphire + 4 Thawing Potions   1 Cobalt Ring   Use this formula to create a Cold Resistance Ring. Any grade of Sapphire can be used. The Cobalt Ring has a random percentage of Cold Resistance
Diablo II 1 Ring + 2 Topazes   1 Coral Ring   21-30 Lightning resistance. Quality of gem and ring ingredients don't matter.
Diablo II 3 Perfect Gems (of any type) + 1 Magic Item   1 New Random Magic Item of the Same Type   Use this formula to get specific statistics on a magic item, especially Exceptional Items.
Diablo II 6 Perfect Gems (one of each type except skull) + Amulet   Prismatic Amulet   Use this formula to create an Amulet with Resistance to all.
Diablo II 3 Perfect Skulls + 1 Amulet   High % chance of getting a +1 or +2 to char skills amulet   Any 3 perfect gems can be used, but skulls seem to have a higher success rate
Diablo II Wirt's Leg + Tome of Town Portal   Opens portal to the secret cow level   Must be done in the Rogue encampment after defeating Diablo on the same difficulty level you have defeated Diablo on.
Diablo II 1 Diamond (any quality) + 1 Staff (any type and quality) + 1 Kris (any type and quality) + 1 Belt (any type and quality) Savage Bardiche
Diablo II 1 Small Shield (magical or better) + 1 Spiked Club (any quality) + 2 Skulls (any quality) Small Shield of Spikes
Diablo II Strangling Gas Potion + any type of Healing Potion 1 Antidote Potion
Diablo II 3 Perfect Gems (of any type) + 1 Magic Item 1 New Random Magic Item of the Same Type You can use this formula to get another chance at a Magic Item of the same type. The ilvl=100. This means that any Magical Prefix or Suffix with a level of 100 or less (which is all of them) is available. You can use this formula (with an Amulet) to create a +2 Skills Amulet. This is helpful because the only monster that could drop one is Diablo on Hell Difficulty (since he's Level 90,). And you cannot Gamble one before Character Level 84. Be warned however, that the chances of getting that on an Amulet might be very low (considering everything is available) and it might take a lot of tries. Rare Items cannot be used with this formula to create new Rare Items.
Diablo II 4 Health Potions (of any type) + Ruby (any type) + Magical/Set/Rare Sword (Any type) Long Sword of the Leech You can use this formula to get a Life Stealing Long Sword.
Diablo II 6 Perfect Skulls + 1 Rare Item 1 Random Rare Item of the Same Type You can use this formula to get another chance at a Rare Item of the same type. ilvl=100. Be warned that if you use a Sword you may get a Socketed Longsword instead. This formula will not work on items larger than 3x2.
Diablo II 3 Perfect Skulls + 1 Rare Item + Stone of Jordan Add 1 Socket To a Rare Item Rare Items can only have one socket. You cannot add more than one socket. You cannot add sockets to items that don't normally have sockets. For Diablo II Exp.
Diablo II 1 Perfect Skull + 1 Rare Item + Stone of Jordan 1 High Quality New Rare Item of the same type This formula has the possiblity of creating a higher quality Rare Item than the following formula. ilvl=66. For Diablo II Exp.
Diablo II 3 Small Rejuvenation Potions 1 Full Rejuvenation Potion Sometimes bigger is better.