The proc filesystem isn't just for learning; it's for tuning and changing parameters. For instance, I have a machine on the Internet that has a five-drive array of disks hanging off a RAID card. Using the "cat" utility, I can find out the status of the drives like so (actual output cleaned up for brevity's sake):

Physical Devices:
0:0 Vendor: QUANTUM Model: QM39100TD-SCA Revision: N1B0
Serial Number: PCB=20-116002-05; HDA=329806
Disk Status: Online, 17782784 blocks, 13 resets
0:1 Vendor: QUANTUM Model: QM39100TD-SCA Revision: N1B0
Serial Number: PCB=20-116002-05; HDA=329826
Disk Status: Online, 17782784 blocks, 13 resets
0:2 Vendor: QUANTUM Model: QM39100TD-SCA Revision: N1B0
Serial Number: PCB=20-116002-05; HDA=329807
Disk Status: Online, 17782784 blocks, 13 resets
0:3 Vendor: QUANTUM Model: QM39100TD-SCA Revision: N491
Serial Number: PCB=20-116002-05; HDA=329831
Disk Status: Online, 17782784 blocks, 13 resets
0:4 Vendor: QUANTUM Model: QM39100TD-SCA Revision: N1B0
Serial Number: PCB=20-116002-05; HDA=329821
Disk Status: Standby, 17782784 blocks, 14 resets
0:6 Vendor: ESG-SHV Model: SCA HSBP M5 Revision: 0.47

Learn more
To learn more about the proc filesystem, go to your Linux kernel source code documentation, usually located on your filesystem under /usr/src/linux/Documentation, for a full list of ways to interact and configure your kernel. Please note that you have to be root to do some of the more interesting things in the proc filesystem.

The proc fs is a terrific way to learn about how Linux works, and I encourage people to explore the proc fs. You can do damage to your system's software, but if you only concentrate on reading instead of writing to the proc filesystem interfaces, the only thing you will need to worry about is messing up your terminal, which you can usually fix by typing in "reset."