the way i got my salary bumped up BIG time was when i was working for a company who had a contract, and my company lost the contract and the new company wanted to hire me. after my current company couldn't place me elsewhere, i ended up going with the new company.
when they asked me what i wanted, i told them $34k more than what i was currently making. i know they needed me more than i needed them so i said screw it and asked them for it. i definitely felt very weird doing that though since it was so much more than i made, and they knew that.
they then came back saying they couldn't do that, but they could do $29k more than i was making.
of course i accepted it, and it set my new "base salary" as a really high level. i've since moved on from that position, and i'm making more than $20k more than i was at that position, and now i have no worries about telling a company how much money i want, because of my current salary and i am good at my job, and i know my skills are worth it.
so moral of the story = reach for the stars. the worst thing they will do is say no and come back with another number. don't tell them what your minimum you will take is. think about that, and then add like $30k to it and just go for it.