Gestalt character

For an exceptionally high-powered campaign of 3rd Edition Dungeons and Dragons, the DM can do more than to allow characters to start out with 32 points for ability scores. They can opt to allow the rules that cater to the munchkin's sweetest fantasies: taking two classes parallel to one another: getting the best bonuses while the lower ones are ignored. Such characters are the famed gestalt characters from Unearthed Arcana, and make for a very high powered game. They are usable for games with only a few players, allowing them to do stuff normally only possible for a party of double the size.

How does it work?

The first step is the same as rolling up any old character: pick a race, roll/buy abilities and stuff. You then pick not one but TWO classes to build your character from! You get the highest Hit Die, Base Attack Bonus, saves and starting gold of the two classes, and use them to build your character with. The reason a gestalt character is so powerful is because you get the Class Features of BOTH classes as you level up! Spellcasting progresses normally but the two are completely seperate from one another: for example your casting as a wizard does not affect your abilities as an archivist. You can even pick levels in prestige classes to level up higher, but this is limited somewhat: you cannot take levels in prestige classes for both classes at the same time, and you cannot pick prestige classes that would advance the spellcasting of two different sources, IE the Mystic Theurge and friends.

The obvious ups to being a gestalt character is that you're powerful as fuck: you are essentially two characters at the same time, which gives you plenty of options even for classes who previously had only limited flexibility. Another usable part of this is that it covers up weak spots that certain classes normally had: suddenly your wizard has a nice hit die, or your fighter gets good saves, or your warmage gets full BAB.

Gestalt characters normally exist in two kinds: the "same but more" and the "double feature". The "same but more" build takes one thing it does well, IE casting, and starts to do the same thing but with two classes, like the afore-mentioned wizard/archivist. The other is the "double feature": two clases that use the same ability but do different things with it, like the bard and the sorcerer.

The downside to playing a gestalt character is that they are only as tough as the best of the two: a fighter//soulknife is only as tough as the fighter, and less tough than an equally-leveled duo of a fighter and a soulknife. The other thing you should keep in mind is that just because you took levels in a martial class you do not suddenly become immune to the effects of armor that affects your spellacasting.

The Hall of Fame

Here's a short list of combinations you might like to tryif you were to play a gestalt character.

Archivist//Wizard

Stand back and throw ALL THE SPELLS. Less powerful than the Erudite pick later on this list, but it doesn't require faffing about with Psionics, for which everyone at the table will thank you for.

Cleric//Druid

Both use WIS and effects to beat the shit out of people in melee. Combine them to make a crazy powerful CoDzilla who can stomp all the face. And dedicate them to Obad-Hai, because it fits.

Dragon Shaman//Warmage/Rainbow Servant

A bit of an oddball: both can fight in melee and get profit from high Charisma (casting for the warmage, healing for the Dragon Shaman), plus getting the full 10 in Rainbow Servant as the Warmage will prove to be VERY useful as a winged, firebreathing and spellslugging badass.

Erudite//Archivist

This is the Spell-to-Power version of the Erudite, allowing you to pull all Arcane spells from peoples' heads. Meanwhile, your divine part of your brain can learn all Divine spells even easier. This class can as such with a combination of good casting, domination effects and plenty of reading learn every spell in the game. Too bad that they're not very tough in a fight.

Fighter//Wild Shape Ranger/Master of Many Forms

An odd combination at first, until you realize you can turn into a Giant, break out a big weapon and beat the everloving shit out of everyone in your way. Or just become a dragon with Fighter feats, for the giggles.

Ranger//Scout

Both of them can do one thing well: shooting bows. Combining the Ranger's tricks and limited spellcasting with the Scout's skirmishing and superior hiding skills you can get a very potent and dangerous archer, picking people off with their bow like it's nobody's business.