The Life of the Deceased
Involvement between the dead and Shaidim/Spirits: R. Chagigah 3b "SheTishreh"
Spirits of the dead affecting the living: Berachot 18b; Shabbat 149b, 152b [2x]
Whether the dead sense their own decay: Berachot 18b; Shabbat 152a
Whether the dead sense what is happening in their cemeteries: Berachot 18a
Whether the dead know who is going to die: Berachot 18b
The dead present at their Eulogy: Shabbat 153a
Rav Nachman appearing to Rava after death: Moed Katan 28a
Rava appearing to his brother, Rav Seorim, after death: Moed Katan 28a R' Chiyya and R' Yonatan walking in a cemetery, and their dialogue on the awareness of the dead: Berachot 18a-b
A pious man who eavesdropped on conversations between deceased spirits about the year's upcoming weather: Berachot 18b Zeiri speaking to his deceased hostess, to find out where his money was stored. She asked him to have her mother send her cosmetics with a certain woman who was to die the next day: Berachot 18b
Ov and Yidoni
[Im-]Permissibility of using a Medium [Ov]: Pesachim 113b [See Rashi, Rashbam "Kaldiyyim"]
What an Ov does: Rashi Keritot 3b "Hoil v'ein bo maaseh"
What a Yidoni does: Rashi Keritot 3b "Yidoni"
Penalty of kareit [Divine excommunication] or bringing a korban chatat [sin offering] for using a Medium [Ov]: Keritot 2a, 7a
Whether we consider summoning the dead via Ov and Yidoni a prohibition performed without a physical action [lav she'ein bo maaseh]: Keritot 7a King Saul using a Medium [Ov] to call up Samuel: Shabbat 152b-153a, Chagigah 4b
Penalty for consulting an Ov and a Yidoni in the same span of forgetting the prohibition: Keritot 3b
Other means of contacting the dead
Sleeping in a cemetery, to acquire Ruach Tumah - Spirit of Impurity: Chagigah 3b-4a [see also Berachot 18b?] Onkelos bar Klonikos pursuing conversion, and consulting his uncle Titus, Bilam and Jews who had sinned, via necromancy: Gittin 56b-57a