Diskeeper is a nice system maintenance utility that lets you see what files are taking a lot of space on your Mac. It can scan any folder on your hard drive and return a graph that will display all the heaviest files in that directory so that you can visually determine which ones are taking your precious hard drive space.
The first step of the process is choosing what folders to scan. Ideally, you would want to scan your entire hard drive if you have space problems. On my Mac, which has a 500-gigabyte drive, the full scan took about 25 minutes, which isn't entirely bad. I noticed that the scans are slower when the app need to scan a lot of small files. If you scan a single folder with only a few large files, the process is almost instantaneous. After the scanning procedure is completed, you will see a graph and you can click on different parts of the graph to see some extra information about them. If what you click on folders, then you will proceed to a graph that shows a scan of that folder. On the right part of the screen, you will find a list of all the files in each folder. You can click on the "Reveal" button located at the top of the screen to show the file in Finder.
This application allows you to delete files by adding them to a Collector. You can add files from different folders to this collector, and when you are done adding files, they can be deleted all at once.
In conclusion, this utility works quite well, it has a good graphical user interface and it can scan folders very fast, especially those with large but few in number files.