Does your dd need a playmate, mine is the same way (also 6mos)!
I would second baby signing. DD can do 5-6 signs and it has already really helped with fussiness. We have a few toys that help. She has a child's computer from V-tech and also a book that plays songs and has buttons on it (also from v-tech) that she really enjoys.
We try introducing lots of new things to her, even stuff that might not typically be baby toys. For instance, I had a recorder at home that I played for her a bit on and then let her play with it afterwards and she loved it!
Also, it helps if she's around other kids, have you tried joining a new mom's support group?
