KDirStat (KDE Directory Statistics) is a small utility program that sums up disk usage for direcory trees, very much like the Unix 'du' command. It displays the disk space used up by a directory tree, both numerically and graphically. It is network transparent (i.e., you can use it to sum up FTP servers), and comes with predefined and user configurable cleanup actions. You can directly open a directory branch in Konqueror or the shell of your choice, compress it to a .tar.bz2 archive, or define your own cleanup actions.
Krypt is a simple application that sits in the system tray and provides easy access to the list of volumes encrypted with LUKS. It is possible to quickly decrypt, encrypt back, mount, and umount such devices. It also monitors HAL activity, and responds by showing a pop-up with password prompt. When the password is provided, KDE's media manager kicks in and does its job. Passwords for volumes can be stored either in a configuration file or in KDE Wallet.
netview lets you browse, mount, and unmount SMB shares using any browser, but especially Konqueror or any browser which is also a file manager. It provides actual mounting of shares so you can edit files on them. It addes mounted shares to /etc/fstab automatically so they will be remounted, and manages storage of passwords in a $HOME/.smbpasswd file for later auto-mounting of shares.