Well, recently i tried some software out and searched and installed.
One that came on to my desktop is the
MediaDownloader. In a nutshell you can play videos from YouTube & Google and local content you may have. Plus you can download them.
Can be installed via Yast.
FsLint is another nice program that can be used for multiple purposes.
It essentially tries to delete older files, dupes, temps etc… although it does have problems to find dupes within pictures. No checksum option.
If you have some programs that are really cool, no body knows about it or have features that are incredible write them down here.
one program I like very much, but I guess a lot of people know it, is pdftk. For folks who don´t know it: this is a command line program to edit, encrypt, decrypt and modify pdf files in every way you can think of. This program is really amazing. It works fast and reliable. Really cool.
Well, i did not know it. Now i will have to check it out 
I think this is an excellent opportunity to exchange programs and tips. More often than not i am looking for programs and don’t know if they exist.
So yes, good tip
Btw. i like to highlight out that a good dupecheck for pictures is within GQView. It is one of the best dupechecks i encountered so far.
Digikam, which is use, has one but is not very userfriendly. So if you need to check your pictures for dupes give GQView a try.
some other apps, which came to my mind:
XBMC Mediacenter, maybe well known? Has a nice user interface and plays your videos and music and you can watch your pictures on your computer. I like it very much
Bibble: is a photo organizing, editing and enhancement program. Unfortunatly it is not for free (as in beer) - it costs money. But I like it better than Digikam (which is also not bad, but…) and it also supports RAW image processing for a lot of cameras.
audiokonverter: is a script for Dolphin. After install you have an additional option in the context menu (rightclick): “Actions”. And when you right-click on an audio file, you can then choose in which audio format you wanna convert this file. It then opens a terminal and processes your request. Very convinient and nice.
and regarding pdftk: it has a good help (pdftk -h) where all the options are explained really good. But it usually takes me around 5 Minutes to figure my command for the task I need 
But this is more likely my own problem, not pdftk´s