Ann Guilbert for these 3:
Seinfeld: Season 3 Episode 5
Seinfeld: Season 7 Episode 14
Home Improvement: Season 2 Episode 23

Curb Your Enthusiasm (Season 5, Episode 4): Ann Guilbert.

Picket Fences (Season 2, Episode 1): Ann Guilbert.

I'm looking for the common name of actress "Ann Morgan Guilbert":

http://www.imdb.com/name/nm0346893/
http://ftvdb.bfi.org.uk/sift/individual/387485
http://en.wikipedia.org/wiki/Ann_Guilbert

Variants: Ann Guilbert (CLT 50/80), Ann Morgan Guilbert (CLT 44/54), Ann M. Guilbert (CLT 1/1), Ann Morgan (CLT 16/55, but there are also credits from another actress with the name Ann Morgan)


Ann Guilbert (18):
Blossom (Season 2, Episode 11) (verified by T!M)
Cheers (Season 7, Episode 20) (verified by T!M)
Curb Your Enthusiasm (Season 5, Episode 4) (verified by T!M)
Grumpier Old Men (verified by SpaceFreakMicha)
Home Improvement (Season 2, Episode 23) (verified by huskersports)
Murder, She Wrote (Season 6, Episode 17)  (verified by T!M)
The Nanny (Season 1, various episodes) (verified by SpaceFreakMicha)
The Nanny (Season 2, various episodes) (verified by SpaceFreakMicha)
The Nanny (Season 3, various episodes) (verified by SpaceFreakMicha)
The Nanny (Season 4, various episodes) (verified by SpaceFreakMicha)
The Nanny (Season 5, various episodes) (verified by SpaceFreakMicha)
The Nanny (Season 6, various episodes) (verified by SpaceFreakMicha)
Picket Fences (Season 1, Episodes 9, 14, 19)
Picket Fences (Season 2, Episode 1)  (verified by T!M)
Picket Fences (Season 3, Episode 7)
Seinfeld (Season 3, Episode 5)  (verified by huskersports)
Seinfeld (Season 7, Episode 14)  (verified by huskersports)
Sour Grapes (verified by ateo357)

Ann Morgan Guilbert (16):
The Andy Griffith Show (Season 8, Episode 13)
The Dick Van Dyke Show (Season 1, various Episodes)
The Dick Van Dyke Show (Season 2, various Episodes)
The Dick Van Dyke Show (Season 3, various Episodes)
The Dick Van Dyke Show (Season 4, various Episodes)
The Dick Van Dyke Show (Season 5, various Episodes)
Emergency! (Season 1, Episode 0)
Emergency! (Season 2, Episode 9)
Emergency! (Season 4, Episode 6)
Emergency! (Season 5, Episodes 15 & 16)
The Ghost Busters (1975) (Season 1, Episode 8)
Good Morning World (Season 1, Episode 3)
A Guide For The Married Man
I Dream of Jeannie (Season 4, Episode 21)
My Three Sons (Season 1, Episode 28)
Two for the Seesaw

Ann M. Guilbert (1):
How Sweet it Is!

Ann Morgan (0):

imdb also lists the following movies/tv shows:
Adam-12 (Season 1, Episode 1)
The Alfred Hitchcock Hour (Season 2, Episode 11)
Amelia Earhart
Barney Miller (Season 8, Episode 5)
Chase
D.A.: Conspiracy to Kill
The Dick Van Dyke Show Revisited
Dragnet 1967 (Season 2, Episode 5)
Dragnet 1967 (Season 4, Episode 14)
Empty Nest (Season 4, Episode 8)
Empty Nest (Season 6, Episode 4)
The Fanelli Boys (Season 1, Episodes 1-19)
Hennesey (Season 3, Episode 9)
Herman's Head (Season 3, Episode 5)
Hey, Landlord (unknown episodes)
Law & Order: Special Victims Unit (Season 9, Episode 1)
Love, American Style (Season 2, Episode 7)
Love, American Style (Season 3, Episode 11)
The Man from the Diners' Club
Maude (Season 4, Episode 16)
Newhart (Season 7, Episode 20)
One Man's Way
On the Rocks (Season 1, Episode 8)
The New Andy Griffith Show (Season 1, Episodes 1-10)
The Partridge Family (Season 2, Episode 4)
Please Give
The Rangers
Room 222 (Season 1, Episode 10)
Room for Two (Season 2, Episode 15)
Second Chance
State of Mind (Season 1, Episode 4)
Viva Max
You're Only Young Once

Please Give: ANN GUILBERT

Getting On: The Complete First Season: Ann Guilbert
Getting On: The Complete Second Season: Ann Guilbert

(Just completed a full cast and crew audit of the DVD profiles for this show in the past couple of days, these credits should be in the system within a day or two).

Picket Fences: Season One: Ann Guilbert
Maude: Season 4: Ann Morgan Guilbert (there are profiles in the system for this as of the moment, but none have cast and crew filled out. I own the Complete Series Boxset and can confirm this is how she's credited here).