There are many Best Of lists. Best RPG, best shooter, best whatever. This list is for players 18 years old and up.
2channelers have picked their favorite erotic games of last year. Here they are (with NSFW embedded links):
1. Sumaga
by Nitro+
Released 26/09/2008
268 pts
2. The Devil on G-string
by Akabeesoft2
Released 29/05/2008
263 pts
3. Rui wa tomo wo yobu
by Akatsuki Works
Released 26/06/2008
212 pts
4. Concerto Note
by Applique Soft
Released 23/10/2008
164 pts
5. Little Busters! Ecstasy
by Key
Released 25/07/2008
153 pts
6. Beat Blades Haruka
by Alicesoft
Released 29/02/2008
115 pts
7. Wizard's Cliimber
by Softhouse Chara
Released 30/05/2008
110 pts
8. Sakura Strasse
by Palette
Released 25/01/2008
105 pts
8. Shikkoku no Sharnoth
by Liarsoft
Released 21/11/2008
105 pts
10. FORTUNE ARTERIAL
by August
Released 25/01/2008
92 pts
Eroge Best Of [via Canned Dogs]