Re: Players Who Have Consistently Threatened the Top
Sandrine Testud (0-1 vs. Clijsters, 2-4 vs. Henin, 3-5 vs. S. Williams, 1-5 vs. V. Williams, 2-9 vs. Seles, 2-12 vs. Davenport [many, many three-set matches], 4-7 vs. Capriati, 1-6 vs. Pierce) is 15-49 vs. these top ten players. Note, she's had the most three set matches with them than anyone else in this poll.
Camille recently has shown her competency against the top players, taking Sharapova to 9-7, stretching Venus mightily, nearly beating Safina.
Those are my two, with Zvonareva battling it out with Conchita.
Serena , Venus , Petra , Ana 
Simona, Vika , Angie, Sveta, Garbiñe
Kim , Mahree , Monica , Dokic, Sandrine, Jie