Without any doubt, Wireshark (formerly called Ethereal) is currently the world's most famous, foremost free and open source network packets capture & analysis tool. Its appearance puts an end to the future of all similar business software.

For guy who wants to be a master of network (WAN/LAN, no matter it's black, red or white), without help of various off-the-shelf classical network utilities for multipurpose uses, I'm afraid your level will stay in the DOS era of last century forever. I mean, in that case, even it was you invented the whole Internet, you could not do anything interesting or exciting.

You can see I put HDD-Profiler into the File & Manage category. Yes, it is an accurate HDD profiling utility designed to compare and display the differences, changes of some folder before/after being used, operated by system, software or some guy.

Because early Windows OS (especially before Windows 7) exists inherent defects on RAM management mechanism. As a result, it's quite common to slow down after running for some time or several large programs. Especially when many programs are running at the same time, which often leads to the RAM exhaustion and Windows crash.

RGS-AvaCam is a freeware all-powerful camera capturing utility, which can automatically and regularly capture (photo and video) through webcam or any other video equipment connected to the computer, and save them to the specified folder.