Somebody on page 1 said k.d. lang couldn’t compare to Patsy Cline, and I can only point out that lang’s band is called The Reclines. I thought we were talking about living singers. LeAnn Rimes struck a lot of sparks, at first, when she was channeling Patsy.
Now that we’re including classical singers, I’d like to say that anytime I hear Kathleen Battle or Cecilia Bartoli, I instantly know that nothing else that day will be any better. 
Based on some of the posts in here, I went out and bought Caetano Veloso’s A Foreign Sound. It’s his most recent album but I did notice that it’s only one of two of his english speaking albums (according to allmusic.com). Did I start off with the wrong one? Because that was pretty close to excruciating (esp. the Nirvana cover)
I too love Holly Cole. Not sure she makes me weak in the knees, but she does indeed have a wailin’ voice.
Sandy Denny
Maddy Prior
Emmylou Harris
Kathleen Battle
“Whisper” is the one that always does it for me. I can’t believe I forgot about Mark Sandman. Jarvis Cocker, too. Lovely deep voices.
Marc Anthony (Mr. J Lo III) has a beautiful voice and is a wonderful singer.
Wow. I’m listening to it now. It hasn’t been out of the CD player in six months. I burned another copy so I could also listen to it at work, which I do damn close to daily.
I’m guessing you’re under the age of 30? Don’t really care for show tunes? I was going to accusing you of lacking irony – but some of it needs to be taken at face value. (His version of “So in Love” is pretty definitive.) Would it help to know that “The Carioca” is from Fred and Ginger’s first movie together, Flying Down to Rio? That one you can take ironically.
I’m 31 , I love crooners but not showtunes (it’s a fine line, ain’t it?) Maybe it’s a grower and not a shower too… I’ve been stuck on one CD I didn’t like at first (Badly Drawn Boy’s “One Plus One is One”) and after over a month of waking up to it in my alarm clock, I really love it. I think my expectations for Caetano were a little high (and I wasn’t anticipating irony, either). I’ll keep it spinning, any others of his I should listen to?
Some great singers here but allow me to add:
Joey Ramone
Also, how Elvis Presley hasn’t been mentioned is beyond me. His range was almost inhuman. Compare Mystery Train to Solitare or the live version of How Great Thou Art. Supreme majesty are the only words that can be used.
Ooh! twickster’s mentioning of showtunes reminded me of two more who make me melt.
Gordon McRae, especially in Oklahoma when he’s softly singing to Laurey at the end of “Surrey with the Fringe on Top.” Dreamy sigh!
Howard Keel, for example in Kiss Me, Kate when he sings the aforementioned “So in Love” or “Where is the Life that Late I Led?” Lusty sigh!
The musical theater women who can make me feel melty and swoony (although not in the same way that the lads do) include Bernadette Peters – especially singing Sondheim – and Barbara Cook, singing anything she damn well pleases.
Nothing to add at this time. I just wanted to flag this thread.
Lillian Leech, especially the song "Smoke From Your Cigarette. "
stpauler (you young whippersnapper 
) – Caetano Veloso has been a massively productive artist for more than 35 years – I’m only somewhat familiar with a few of his albums, and am still working my way through his oeuvre myself. (If anyone has some recommendations, I’ll be happy to follow up on them.) Link to his AMG discography – note that you can listen to samples of songs if you click on albums. There were also samples on the page I linked to in the OP. Another album I enjoy a lot is Tropicalia 2, an album he did with Gilberto Gil, another Brazilian great (who is now, I believe, the Minister of Culture there).
And remember – it’s the voice. I described it once as something I wanted to rub big handfuls of all over my body.
Keep listening – I’ll be curious to find out if it grows on you. And – BTW – I still don’t know wtf to make of his version of “Feelings.”
As I had mentioned in one of my previous posts. 
Anyway, if you want a good overview of some of the best MPB (Musica Popular do Brasil) you should look into getting Brazil Classics 1: Beleza Tropical, and Beleza Tropical 2: Novo! Mais! Melhor!. The Samba and Forro albums from Luaka Bop are also very good. Forro sounds like a Brazilian version of Zydeco. My personal favourite Caetano album is the one where all the songs are live performances with his sister Maria Bethania, called:
Chris Isaac definitely makes me go weak in the knees. If I were ever to hear him live, all that would be left of me is a puddle on the floor.
And I don’t know if it’s so much the voice, or the combination of everything, but James Marsters as Spike. Izzybella has been playing the soundtrack for “Once More With Feeling” at least twice a day for the last month at work, and every time I hear Spike sing the line, “If my heart could beat, it would break my chest,” my knees quiver.
Well, since I’m at work, now I have to try to calm down. Lessee . . . [Austin Powers]"Margaret Thatcher naked on a cold day![/Austin Powers] eeeeuuuuwww
Is that where I heard it? :smack:
Oh, and Mycroft – what do you think of A Foreign Sound?
Well, it’s … ummmm. different? it definitely grew on me, but I’m not that big a fan of Morelenbaum (the cellist and main arranger on the album). Then again he has Carlinhos Brown on percussion, and I love his music. Have you heard "Tribalistas " yet? It’s probably the best Brazilian album of the last two years.
Anyway, if I’m in the mood for Caetano (which isn’t always the case), I prefer “Noites do Norte” or “Fina Estampa”
Getting back up on topic of “Which singer’s voice makes you weak in the knees”, how could I have forgotten Amália Rodrigues, the queen of the Fado.
Of those mentioned:
Beth Gibbons
Elizabeth Fraser (before I finally got arount to the Cocteau Twins, my first acquaintance with her was through Massive Attack’s single “Teardrop.” I absolutely melt everytime I hear that song.)
Bjork (especially the a capella work on her new album, Medulla.)
Neko Case
Of those unmentioned:
Jane Birkin (especially her work with Serge Gainsbourg)
Brigitte Fontaine
Isabelle Adjani (I’m not totally convinced I like the music, but her voice on “Pull Marine” sends chills up my spine.)
Ohhh, a lot of the knee-weakage involved lyrics/production/etc. So, why didn’t you include Sugarcubes Birthday 
It totally blows away anything else by them or Bjork, whereas Emiliana Torrini sometimes comes close, but the mood created by the production and the music elevate Birthday to a plane higher than even good chanteuse ballads.