Following four commands can be used to get a list of local devices which are online. They provide different types and format of informatione. Thank you rpi444from the raspberry Forum for the list of commands.
 
It's easy to create a tunnel for a proxy with putty. You have to install putty first. Then configure a tunnel with connection -> SSH -> Tunnels  (see following screenshots). This will tunnel the local port 3128 with ssh to the remote host port 3128. Now port 3128 is the standard squid proxy.
namebench is a tool, which allows to measure the performance of DNS nameservers. That way you can find out which DNS nameserver you should configure on your system in order to get optimal nameserver performance.The test needs some time - but the results are very helpful.
At home I use a Linux server as a disk- and printserver. I wanted to grant somebody from the United States using Windows access to my shared disks which are available on my sambe server. It's not an issue on my local LAN but it's dangerous to open disk shares in the internet. It's just a matter of time until you have foreign visitors accessing your LAN. The best way to solve this issue is to create a VPN with OpenVPN. An alternate way is to use a ssh tunnel. The following article explains how you can get this done on windows XP with PuTTY.  Windows7 unfortnately is much more complicate and works best with a VPN network.
 

Recently I had problems to revoke my labtop from the supend mode. Finally I wasn't able to use KNetworkmanager any more because it was disabled.  Seems to be a feature of openSuSE 11.3  Solution: Edit /var/lib/Networkmanager/Networkmanager.state and change NetworkingEnabled=false to true

See also here

Update 9.August 2010: Bug fixed

 
I usually use my webdav space from my Linux systems. But I also want to use this webdav space from my Windows box with filemanager TotalCommander. There exists a plugin in the plugincollection which is installed very quickly. The documentation how to configure and how to use the plugin is not very detailed. I found here a much better description how to use webdav with TotalCommander.

If you want to use webdav space with Linux there exist various ways to connect this space to a Linux system.

 
1) wdfs - Very easy to use. It's a simple command line and then you can access the webdav space from a console or any filemanager.
2) davfs - You have to configure this first. Then you can use it the same way as wdfs. The way it's used by Linux is identical to the other spaces like disks, nfs, smbfs which are used as filesystems in Linux. davfs is my suggested way to use webdav in Linux.
3) cadaver - Works similar like a ftp or smb client on the command line
 
There exist variouse filemanagers like dolphin and krusader which offer their own way to connect to a webdav space. If you use wdfs or davfs you can easily use these filemanagers to work with webdav space transparently by a mount point.
 
I personaly use davfs because the webdav space is used the same way in Linux like all other space is managed. I can use my dolphin or krusader easily to access the webdav space.
 
There is another article which describes how to use webdav with totalcommander.
 

There are not much free IPV4 addresses available any more and it will not take very long until a home user also has to use IPV6 addresses.

 
I found following pages helpful to get familiar with IPV6.
 

I had bad network performance in my local network. I added following lines to /etc/sysctl.conf and disabled ipv6 and now everything works fine again:

net.ipv6.conf.all.disable_ipv6=1
net.ipv6.conf.default.disable_ipv6=1
net.ipv6.conf.lo.disable_ipv6=1

WLAN has a major advantage compared to wired communication: You can use your laptop, iphone or android everywhere and don't have to struggle with a cable. Just comare it with wireless and wired phones. There are some disadvantages: WLAN has usually a lower throughput than wired connection. But that's acceptable for normal browsing, eMail processing and chatting. Unfortunately there is another disadvantage: The number of WLAN channels to communicate with the accesspoint is limited. If a neighbour uses the same channel or a channel nearby the throughput of WLAN will decrease significantly.

 
You have to configure in the advanced network connection to use a proxy. Then you use th local port 3128 as the proxyport which is tunnels with ssh to the remote server on port 3128.  This trick can be used for any port which should be tunneled.