Martina Navratilova alone is a source for many amazing feats. Here are a couple:
74-match winning streak, following on the heels of a 54-match streak. During this period, she went a mind-boggling 128-1 and won 6 straight slam singles titles (a record).
Never lost a Fed Cup match in singles or doubles.
Spent over 1000 weeks in the top 5.
20 straight quality finishes at Wimbledon.
119 singles wins at Wimbledon. If someone played Wimbledon 17 times, and won it every year, they'd just tie her (assuming no walkovers).
Won a slam singles title in 3 different decades.
Reached finals of every slam event held in 1985 (Singles-Doubles-Mixed), the only player in history to do so.
And of course, Graf has some as well. Here are a few (numbers off the top of my head, don't have the info handy. I'm sure someone will correct me if I'm mistaken.):
186? consecutive weeks at #1; longest such streak ever.
Most weeks at #1. (377? 378?)
Won each slam singles title at least 4 times.
Some other player tidbits:
Virginia Wade played the Wimbledon singles 24 straight years. I believe it's also Wade who holds the record for Fed Cup singles wins. (Rollo? Zummi?)
Barbara Jordan was the first American woman to win the Australian Open. (Read that carefully.)
Chris O'Neil's only career singles title was the Australian Open. She was ranked 111 at the time.
Dally Randriantefy has never lost a Fed Cup singles match.
Katerina Studenikova has all 5 vowels in her surname.
Billie Tapscott was the first woman to play Wimbledon without stockings, in 1929.
The 1st Japanese player to play Wimbledon was Zenzo Shimizu, who played the men's singles in 1920.
Hana Mandikova was the first woman from a non-English-speaking country to win the Australian Championships, in 1980. The firsts at the other 2 English-speaking slams were Suzanne Lenglen at Wimbledon in 1919, and Anita Lizana at the US Championships in 1937.
At the first official Championships of Hungary in 1894, the men and women competed against each other in the singles draw. The tournament was won by a woman, Paulina Palffy.
Jadwiga Jedrzejowska was the #1 ranked woman in Poland from 1928-1959.
The 4 Fernandez sisters who played in the 70's and 80's were comprised of 2 sets of twins. In the 1977 Southern California High School Championships doubles final, one set of twins, Anna Maria and Lucia, defeated the other, Cecilia and Elisa.
As for the tallest player ever, I'd give the nod to Brenda Schultz-McCarthy. She was listed anywhere from 6'2" to 6'3", yet looked even taller than that.