Yesterday expanded my bootcamp partition from 50 up to 100 Gb using Mini Tool Partition Wizard Home Edition, a Freeware Windows Program after seeing this video: http://www.youtube.com/watch?v=WeKeawqxUa0
Note that I have OSX Mavericks, Steps are:
1) backup all your files (optional but strongly reccomended).
2) Using OSX Disk Utility resize MacintoshHD partition leaving unallocated space as much as you need to add to bootcamp partition.
3) Set Bootcamp as Boot Disk and restart the mac.
4) in Bootcamp with Windows running launch Mini Tool Partition and select the bootcamp partition.
5) Choose "expand" option in order to expand the partition using all the unallocated space.
6) The program prompt to you to restart the mac for apply the task, cause is not possible while the partition is mounted and windows running.
7) Restart the mac and then automatically Mini Tool Partition will do the job in a "graphic msdos like" form.
I was lucky and worked for me, I have a Late 2009 Mac Mini with MAVERICKS and a samsung 250Gb SSD Evo.
Hope this can help the community but decline any responsibility, do it at your own risk, you can use programs like winclone or camptune if you feel more comfortable with a pay app.