Subjective Mood (Le Subjonctif)
Subjunctive: express desires, doubts, the unknown, the abstract, and emotions
Indicative: express actions, events, and states that are believed to be true and concrete

The subjunctive mood is used to express actions or ideas which are subjective or otherwise uncertain:
doubt (subjunctive with expressions of doubt)
possibility,(subjunctive with expressions of possibility)
necessity, (subjunctive with expressions of necessity)
emotion, (subjunctive with expressions of emotion)
will/wanting (subjunctive with expressions of will and wanting)
judgement (subjunctive with expressions of judgement)

Subjunctive expressions of:
Preferences, Advice, Needs, Desires, Orders (PANDO)
Judgments, Emotions, Feelings (JEF)
Possibilities, Opinions, Doubts, Suppositions (PODS)
(some of these verbs call for the ne explétif)

Subjunctive indicating purpose
subordinate clause indicating purpose
Subjunctive and implicit negation
Subjunctive with conditional expressions
Subjunctive with superlatives expressions que nous ayons
(mentions subjective context – within a limited frame of reference vs absolute)
Subjunctive in relative clauses after qui and que to specify things that exist in the speaker’s mind but that may not actually be available in reality

Introducing the French Subjunctive french.about.com
Understanding French Subjunctive frenchtoday

Simple Tense:
Present subjunctive
Imperfect subjunctive

Compound Tense:
The Past Subjective Passé du subjonctif
Pluperfect subjunctive

Completely Irregular Subjective Forms
aller, pouboir, savoir, faire
avoir, être, aller, valoir, vouloir
aller, falloir, valoir, vouloire
forms of the Subjunctive cliffnotes.com

Verbs
Elements of Grammar