30 Rock
A full list of special holiday episodes
Liz Lemon is the head writer of sketch-comedy show. She juggles a new arrogant boss, a crazy star, and the show's success without losing her mind.
The show aired 4 Christmas episodes, and 5 Valentine's Day episodes.
Christmas episodes:

Season 2, Episode 9
Ludachristmas
Jack finds solace in the love and support of Liz's parents, while Kenneth disrupts the staff's plans for a wild holiday party.

Season 3, Episode 6
Christmas Special
Jack accidentally hits his mother with his car and is forced to care for her while she recovers. To lift her spirits, he puts on a Christmas special with the help of the staff. Meanwhile, Liz buys toys for a 'Letters to Santa' program as her mother is not hosting a family Christmas.

Season 4, Episode 8
Secret Santa
Jack reunites with a former crush from a social networking site, the writers create a fake religion to avoid participating in Secret Santa with Kenneth, and Pete seeks revenge on Jenna for not contributing to a Christmas gift.

Season 5, Episode 10
Christmas Attack Zone
Jack invites his father and Avery to Christmas dinner to ambush his mother, Jenna misses her ex on "New Queers Eve", and Tracy tries to maintain his new "serious" image.
St. Valentine's Day episodes:

Season 1, Episode 13
Up All Night
Liz forces staff to work on Valentine's Day, receives mystery flowers. Jack finalizes divorce with Bianca and celebrates with Tracy who is role-playing in a hotel room. Jack brings a hooker there.

Season 3, Episode 11
St. Valentine's Day
Liz's Valentine's Day doesn't go as planned with Dr. Baird, Elisa drags Jack to church, and Kenneth goes on a date with a blind woman with Tracy's help.

Season 4, Episode 13
Anna Howard Shaw Day
On Valentine's Day, Liz is stranded after her oral surgery, Jack goes on a date with a journalist, and Jenna confronts her stalker's infidelity.

Season 6, Episode 6
Hey, Baby, What's Wrong?: Part 1
Liz and Criss go to IKEA and encounter relationship problems, Jack develops an attraction to his mother-in-law, Kenneth trains his assistant, and Jenna experiences stage fright.

Season 6, Episode 7
Hey, Baby, What's Wrong?: Part 2
Criss and Liz go shopping for a dining room table on Valentine's Day, while Jack spends time with his mother-in-law. Meanwhile, Jenna scrambles to find a replacement producer for her upcoming live performance, and Tracy and Frank help Lutz find a date for Valentine's Day.