Maria-sama ga miteru -- girls school drama with very strong subtext, and Sei is nigh-canon lesbian (fansubs only 3 series)
Kasimasi ~ Girl meets Girl -- A boy is turned into a girl by accident, and ends up deciding which of two other girls should be vis girlfriend. Yuri kisses in the first ninety seconds of episode 1 -- US release 2 disks out of 3 already out
Strawberry Panic -- girls school drama with girls ending up in bed together, just not H material
Magical Girl Lyrical Nanoha -- Very heavy sub-text : Nanoha's first reaction to the rival magical girl she meets is to remark on her beautiful hair and sad eyes, and to admit she has strange feelings about her. By the third season, they are sharing a bed and bringing up a daughter together -- first 2 seasons in Geneon licensing limbo.
Simoun -- everyone is born female, and chooses sex at adulthood. Yuri tongue wrestling is needed to activate their flying machines; and appears in close-up in the OP sequence. Includes one canon yuri->yaoi couple.
Blue Drop -- Lesbian aliens want our women