No microphone recording with Skype (and elsewhere)

I had made several not very earnest attempts to place Skype calls from openSuSE, which failed on three different machines (a Samsung R55, an ASRock and an Asus board) as the microphone was not recording anything. Sound output worked. Three things to check:

1. Sound volume settings in YaST: I had Mic actually down to zero because of some feedback noise in my Line out. Also, look at the channel settings in the alsamixer console tool - the YaST mixer doesn't list all channels. Check whether the capture is set to the right channel and whether any volume is 0 that shouldn't.
   
2. The 'Sound in' Default device setting in Skype menu->Options->Sound devices didn't work. I had to choose an explicit device (took the first in the list at random) to record anything. No idea what Skype supposes the default device to be. With 'Sound out' the default setting works fine. This did it for Archimedes.
   
3. This affects microphone input in general (check 10 s recording from a shell with arecord -d 10 test.wav, or audacity). Sometimes ALSA assumes a wrong model for your sound card or codec.
   Get the necessary information from arecord -l:
   
   card 0: M5461 [HDA ULI M5461], device 0: ALC861 Analog [ALC861 Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
   
   Edit /etc/modprobe.d/sound:
   
   options snd slots=snd-hda-intel
   # MZfG.1be8IFnUvYA:High Definition Audio/AC'97 Host Controller
   alias snd-card-0 snd-hda-intel
   options snd-hda-intel model=asus-laptop
   
   If you use a different codec or soundcard model, check the codec list in ALSA-Configuration.txt. Actually, try all possible options until it works: for Xanthippe's ASRock 939 desktop board (ULI M5461 chip with ALC861/660 driver) the 'asus-laptop' option worked, while 'auto' didn't.
   I restarted the module with su -c 'rcalsasound restart'
   Here, KDE wanted to forget about some allegedly removed devices: I opted cautionarily against it (it's KDE 4 Factory, after all). KMix was shot down and had to be restarted by hand. Skype and Audacity recording performed faultlessly, arecord was a bit thin and noisy (I can live with that). Did it for Xanthippe and Tisiphone.
   
4. Try the diagnostics offered in this forums.opensuse thread or the openSuSE SDB. Note that tsalsa is available as a Packman package.
5. If nothing helps: A cheap USB external sound card might do the trick.