Is there a tool that let me (recursively) visualize how much diskspace space directories and files (!) consume on my disk and that lets me delete directories and files (!) which would result in a on the fly update of the visualization. Something like HDGraph only that it also shows the size of the files separately and that it has a delete function.
SpaceSniffer brings up the standard Windows context menu on a right-click, so yes, it can delete.
It updates instantly as well (even from things outside the application, which is awesome to watch!)
I found WinDirStat a while back and found it to be awesome. You can delete files from within the application. You can also do it outside and then right-click any part of the directory tree and have it refresh it quickly.
TreeSize does it very well, and the pro version has a nice pie chart and bar chart - if the starburst chart of the alternate tools is not your taste.
I mostly use the excellent freeware Folder Scanner.