What is consuming HDD space on my MacBook Pro?
Sounds like you need a disk visualizer. There are several out there:
Disk Inventory X (free)


Disk Inventory X is a disk usage utility for Mac OS X 10.3 (and later). It shows the sizes of files and folders in a special graphical way called &quot;treemaps&quot;.

It is my personal favorite, as it is really simple and easy to use, as well as the great price of free!
DaisyDisk ($20, currently on sale for $9.99)


DaisyDisk scans your disks and presents their content as interactive maps where you can easily spot unusually large files and remove them to get more free space. The map gives you an overview of your data, so you always know what your hard disks are filled with.

I don't have personal experience with DaisyDisk, but it has been highly recommended by many people, including members of Ask Different.
GrandPerspective (free)


GrandPerspective is a small utility application for Mac OS X that graphically shows the disk usage within a file system. It can help you to manage your disk, as you can easily spot which files and folders take up the most space. It uses a so called tree map for visualisation. Each file is shown as a rectangle with an area proportional to the file's size. Files in the same folder appear together, but their placement is otherwise arbitrary.

Again, no personal experience, but highly recommended by others.