We all see those guys that sit there and dabble on their computers at local coffee places, and you may be one of them (lord knows I am). Well, I've got a field tested opener for them.
If an HB sits in proximity of you while you're sitting there doing what you're doing (probably on this site), wait a short bit and do this...
Are you ready?
Ask her to watch your computer while you go to the bathroom.
I know, it's simple, it's trivial, but it works. Of course, ask loud enough so people around know that she's watching it so she doesn't walk off with it. I typically throw in some C&F, and some minor push/pull to get it started, but then I go to the bathroom (it doesn't matter if you have to go) and come back and do some teasing to further build rapport. Here's a typical example...
PUA- Hey there, this may sound strange, but you look like a semi-trustworthy person. Are you?
HB- Ha ha, yes.
PUA- Well then, next I'll have to ask if you're someone who could be considered adventurous at times.
HB- Of course.
PUA- Ok. I've got a strange request for you, and it requires little effort on your part. Are you ready?
HB- Uh, sure.
PUA- It's literally life or death, like a top secret mission type thing. You still think you're up for it?
HB- Ha, alright.
PUA- Ok, can you watch my computer/coffee as I go to the restroom? Ha ha, told you it was life or death!
HB- Ha ha, yeah I can do that.
Then I go, and when I come back I typically ask them how the mission went, tease them about going through my stuff on the computer, etc. I generally use the "yes ladder" in the beginning, and I always bridge into other topics of conversation after I return. I've used this on numerous sets and it works every time. Number closes usually are the end result, or I suggest a venue change.
Have fun!

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nice one man. get her interest peaked and then leave. then while your gone she's thinking about you and something snappy to say when you get back. definetly give this one a try.