Old stuff made long time ago by Caelic, but still worth it as far as I'm concerned:
Caelic's "The Ten Commandments of Optimization"
I. Thou shalt not give up caster levels.
II. Wieldest thou thy two-handed weapon with alacrity; but two weapons shalt thou not wield, excepting that thou hast a source of bonus damage such as Sneak Attack.
III. Doubt not the power of the Druid, for he is mighty.
IV. Avoid ye the temptation of Gauntlets of True Strike, for they shall lead thee astray down the Path of Non-Rule Cheese.
V. Thou shalt not give up caster levels. Verily, this Commandment is like unto the first; but of such magnitude that it bore mentioning twice.
VI. Makest thou no build with an odd number of fighter levels, for such things are not pleasing to the Spirits of Optimization.
VII. The Rules of 3.5 are paramount; invoke not the rules of 3.0 if a newer version be available.
VIII. When beseeching the Bretheren of Optimization, come thou not empty handed, lest they smite thee; rather, bringest thou thine own build, that they may offer suggestions and guidance.
IX. Invoke not "common sense," for it is not common.
X. Thou shalt call no build "The Ultimate X" unless his name be Pun-Pun, or thou shalt see thine "Ultimate" build topped by the Bretheren within five minutes of posting.