Well, we have a topic for our favorite visual novels, but let's see which one's everyone has played and own. Here's my list of games I own and played (mostly own, note I don't know Japanese (or much anyway) so most of these have patches or are lisensed... yay me. And please don't judge me on the content of my collection... if it's English I'll play it):
PC:
True Remembrance
Narcissu
Ever 17 ~Out of Infinity~
AnimaMundi: Dark Alchemist
Utawarerumono
Saya no Uta
Tsukihime
Yume Miru Kusuri
Yo-Jin-Bo
Enzai~ Falsely Accused
Absolute Obedience (Zettai Fukuju Meirei)
Silver Chaos
Silver Chaos Fanbox: Eternal Fantasia
Clannad
D.Nd: Poisoned
The World of Haruhi Suzumiya (the demo at least)
Fate/Stay Night
Higurashi no Naku Koro ni
Umineko no Naku Koro ni
Other various English made and translated freeware visual novels
DS:
Phoenix Wright: Ace Attorney
Phoenix Wright: Ace Attorney- Justice for All
Phoenix Wright: Ace Attorney- Trials and Tribulations
Apollo Justice: Ace Attorney
Trace Memory
Hotel Dusk: Room 215
Lux-Pain
In the future, I plan to get even more of these game, including Chaos;Head and Never 11 ~Out of Infnity~