One of my closest friends had Aspergers and as a result she has difficulty keeping good friendships and her parents bully her about it. She keeps asking me for help and I try my best but I'm not sure how much more I can do. What can I do to help her?

It sounds like her parents are not acting responsible in this situation.  I have a close friend with Asperger's, and his parents have done a ton of research and stuff and find out what works best with him.  It's really sad that your friend's parents aren't stepping up to the job.  You just need to be her friend, but it will help if you do a little research as well.  It will help you some, but there are no rules.  

Remember that no Asperger's case/situation is the same, so there will be things you find in your research that will be very similar to your friend, and other things that won't be like her at all.  As for her parent situation, I'd advise having her talk to a counselor.  Try to convince her, but if you can't you might just have to talk to a counselor yourself.  Parents play a huge role in how their children grow and mature.  I know Asperger's kids with great parents, who have learned to deal with the world more quickly than kids whose parents don't care, or don't try to parent their child based on their needs.  

Good parents make things easier on the kids, and this definitely applies to every kid.