An English accent will melt my knees every_single_time. Not just any English accent, none of this Lond hackney crap, but a proper, smooth-tongued English gentleman.
Noname: I can do this. 
How you doin?
Kya, yaar!
Aaaaa! *London * accent! WTF is a Lond accent?
I really, really like the Hindi or Arab accents. I worked with a group of women from India a few years ago, and it was everything I could do not to bow before them every single day.
goes weak in the knees
I am especially fond of the female southern accent.
- Israeli women, from Israel (not Americanized)
- Irish
- Many African accents are simply beautiful, although difficult for me to pinpoint country of origin.
New Zealand accents make me purr.
As do Australian.
Almost any female voice with good diction - none of your Sloane, Cockney, Brummie, or Scouse rubbish - is good, but I do like the Scottish accent.
French is wonderful on a woman. Also I had a college classmate who was from Trinidad and her voice was like small bells pealing. I still have fantasies about her voice though many moons have passed. Most of the island countries have interesting accents on the right people.
Somebody mentioned a Filipina, and I’m not sure about them having Malay* accents, but the many Filipinas that I worked with, while very nice people, had accents that I found vaguely annoying. Some Thai accents are nice and others are not so nice. I do like Japanese accents, but not necessarily in a sexy way, maybe more like cute.
*It’s probably going to depend a lot on where a given Filipino is from.
I used to work for someone who came to the US from Italy, and apparently women really liked his accent. According to his secretary, it wasn’t unusual for women in the building to call his office when he was out, just so they could listen to the message on his answering machine.
Well a Scottish accent is best.
But are we talking Northern, Southern, East or West?
Irish, Scottish, and British. Yummmmmm.
Brazilian Portuguese accent, but not the Portuguese accent from Portugal (they speak to nasally). I’m not just saying that because my wife is Brazilian. Brazilian has to be the sexiest, most musical language known to mankind. French or Italian don’t even come close. You think Carmen Miranda was popular because of the hats?
I don’t know if this counts, since I’m not sure this is an accent, and it only affects me with my husband, but I just love his Canandian “ou” sound. You know the one. Out, about, route. Sigh…I actively listen for it on TV because he hasn’t been around for so long, and text messages have no accent. But of course, it isn’t the same, anyway. Has to be Glenn, or no good.
However, I must admit that Sean Connery, no matter how old he gets has a voice that makes my motor run. I guess I’d just have to close my eyes. Sorry, Glenn!
A-bloody-men. I haven’t spoken like that in months, but it’s very nice when I do around some girls… Let’s just say that it’s well-liked in some circles.
(And by the way, I think you mean ‘Cockney’, which I also abhor, not ‘hackney’)
Any accent except the New Jersey whine is big time sexy.
Irish accents, boy howdy. I had no idea how much until I went out on a pub crawl in Dublin. I kept meeting people and thinking, “I wonder if they’d be offended if I just closed my eyes while they talked.” Even random phrases from the tour bus driver, like “Dublinia and Saint Padrick’s Cataydral, ye get free admission ta bode a dose.”
I used to think the Scottish accent did it for me, until I watched a lot of Scottish TV in that same trip. I just found it comical. (No offense intended.) Also, seeing Trainspotting pretty much killed that for me.
Another one is the New Zealand accent – Australian, not so much. I watched the commentary version of The Two Towers about a dozen times, only partly because I’m a total nerd. Mostly it was to hear Peter Jackson and Phillippa Boyens talking. “It’s just a SLIGHT DEPATCHA from Tolkien’s work.” Sigh.
My only personal experience with Brazilians is a woman who works at my office whom I occasionally speak with both by phone and face-to-face. I find her accent utterly entrancing. 
Celtic (Ewan McGregor and Slavic (Goran Visnjic)
maybe I’m alone here, but nothing makes me melt faster than a man with a smooth tenor/baritone voice and a Southern accent. I’ll call my friend Clay up (he’s from Atlanta) and let him ramble on at me for hours, just to listen to that accent. Man, it makes me shiver, especially when he’s a little on the drunk/stoned side and the accent’s even MORE pronounced… I even like the stronger Southern accents, like the Alabama one. Another friend of mine has a GREAT Alabama drawl that I could just listen to for hours.
I also like British and Australian/New Zealand accents.
Undoubtably I’ve been influenced by women of my past acquaintance: East Texas, Irish and a certain New Orleans (there’s more than one accent running around The Big Easy - I’m thinking of the one that describes the city as Nue-Wahlins).
Hmm, well, I’ll take Southeast Texas as well.