Massuh,
I see your questions below and I do intend on answering some of your questions eventually. But you ask another interesting question in your last posting.... You say :
The thing I can't figure out, is how come it doesn't say in the Bible "And G-d created Hell" on one of those six days?"
Well, as you know the Jewish sages do not leave any question unanswered. Judaism is one of the only religion which goes out of its way to ask and answer all questions. Of course we know when Gehinnom was created from our Oral Tradition.
Here are some interesting tidbits from the Talmud on the subject of Gehinnom:
http://www.webshas.org/emunah/gehennom.htmHell - Gehennom
Links
The Angel of Hell
Satan and the Angel of Death
Divine Reward and Punishment
The Next World - Olam HaBa
General Details
Details of the valley known as "The Valley of Ben Hinom" - "Gei ben Hinom": Eruvin 19a; Succah 32b
The openings of Gehennom in the desert, the sea and Jerusalem: Eruvin 19a
The breadth and width of Hell: Pesachim 94a
Hell was created before the Universe: Pesachim 54a; Nedarim 39b
When the "Mouth" of Hell was created: Nedarim 39b
Its fire was created on Day Two of Creation: Pesachim 54a Better to receive punishment in this world, rather than after death: Pesachim 57b
Those who remain in Hell past 12 months: Rosh HaShanah 17a
Isaac's merit keeping the Jews from Hell: Shabbat 104a
Why Gehennom has the name "Gehennom": Eruvin 19a
Gehennom is also titled "Yam Kol [Sea of All]" because so many go there: R. Shabbat 104a "LiYam Kol"
Gehennom is also known as "Tifteh": Eruvin 19a
Gehennom is also known as "Sheol": Eruvin 19a
Gehennom is also known as "Avadon": Eruvin 19a
Gehennom is also known as "Be'er Shachat": Eruvin 19a
Gehennom is also known as "Bor Shaon": Eruvin 19a
Gehennom is also known as "Tit haYavan": Eruvin 19a
Gehennom is also known as "Tzalmavet": Eruvin 19a
Gehennom is also known as "Eretz haTachtit": Eruvin 19a
Gehennom is also known as "Paku": Megillah 15b
Gehennom is also known as "Raah [Evil]": Nedarim 22a, 40a
Rage causes one to be afflicted by "types of Hell": Nedarim 22a
When Avshalom was hanging, he saw Gehennom open beneath him: Sotah 10b
King David cried out over Avshalom, "My son," eight times; this brought Avshalom out of seven levels of Gehennom, and either caused his head to come back to his body, or brought him into the next world: Sotah 10b
Groups of People in Hell
People who are arrogant: Sotah 4b-5a
When humans punish a wicked person, they have to shut the wicked person's mouth to keep him from slandering them; Gd punishes the wicked in Gehennom, and they admit His justice: Eruvin 19a
Whether the wicked repent at the entrance to Gehennom, or not: Eruvin 19a
The punishment of those who cause others to sin carelessly, with their bodies: Rosh HaShanah 17a [2x]
The Definition of the Above category includes Jews who don't wear Phylacteries: Rosh HaShanah 17a
The Definition of the Above category includes non-Jews who reign with terror, or who cause sexual sin: Rosh HaShanah 17a
The punishment of opponents of Torah: Rosh HaShanah 17a
The punishment of Those who Betray their People: Rosh HaShanah 17a
The punishment of heretics: Rosh HaShanah 17a
The punishment of those who act separately from the community: Rosh HaShanah 17a
The punishment of those leaders who cause others to fear them: Rosh HaShanah 17a
The fate of Yeravam ben Nevat: Rosh HaShanah 17a
The punishment of those who embarrass others: Bava Metzia 58b
The punishment of those who alter others' names, even if the nicknames are common: Bava Metzia 58b
The punishment of adulterous men: Bava Metzia 58b
A person who is adulterous will end up in Gehennom, even if he is a Torah Scholar: Sotah 4b
A person who listens to his wife's advice in certain areas, as King Achav did, will end up in gehennom: Bava Metzia 59a
Anecdotes involving Hell
Korach's children were saved from descending into Hell: Megillah 14a
When Nevuchadnezzar descended to Hell, the people there thought he had come to rule them, until a Bat Kol [Divine Voice] put him in his place: Shabbat 149b-150a
Avraham saves his descendants from Gehennom, unless they intermarried: Eruvin 19a
Attributes/Acts which prevent entry to Hell
Jews are protected from the fires of Gehennom by their Mitzvot: Eruvin 19a
Humility: Yevamot 102b
Fear of sin: Shabbat 104a
Awe of HaShem: Yevamot 102b
Charity: Gittin 7a
Visiting the Sick: Nedarim 40a
Care in enunciating the words of Shema merits a chilling of Hell: Berachot 15b
Suffering poverty: Eruvin 41b
Suffering intestinal disorders: Eruvin 41b
Suffering from money-lenders: Eruvin 41b [according to Rashi]
Suffering from a harsh government: Eruvin 41b [according to Tosafot]
Suffering from a bad spouse: Eruvin 41b
Other
Titus's attempt to avoid posthumous Divine punishment via cremation and scattering of his ashes - and how the tactic failed: Gittin 56b-57a