The best openers are the ones that are coincidential. By that, I mean openers that are natural and arise from something that has just happened.
Let me give you an example of a couple of openers that I used last night...
I was at a bar, girl is walking past a table of 5/6 guys, and she passes one of them this ugly, fat mo'fo' reached out and grabbed her hand. Then attempted to talk to her. She was just polite, smiled, turned him down gently and carried on walking. As she got close to me she saw me looking at her, smiling. As she got close enough to hear me..
Me: NICE! I think you've pulled there!
Her: ha ha ha ha ha. I know! I cant believe how some guys think they can just grab you like that.
Me: mmmm I know! thats terrible! I NEVER do that!
And then I just grabbed her hand, and gave it a squeeze. She squeezed back. We fluffed abit. I got her to qualify her self to me (Can you cook?) bla bla. Number closed her and moved onto the next bar.
As I was walking in, I noticed two seriously HOT HBs sitting just inside the entrance. I went with the 3 second rule and approached them straight away..
Me: Damn! tell me you didnt see that!
HB7: see what?
Me: phew! not to worry, have a good night
HB7: no tell me! what happened?
Me: well you know when you walk towards the door, and you are not sure whether you are suposed to push or pull??? well I pushed, the door didnt moved and i kinda walked straight into it!
HB7: ha ha ha ha ha. oh.... i cant believed i missed that!
Me: oh gee! thanks! So what brings you ladies here anyway....
Then i slowly progressed, sat down and took it from there...
Also, look up some of mine and Shezz's FRs. They have loads of examples of openers in bars.
Good luck!