Thanks stardepp, well done! I want to make a suggestion for your Discogs "Artist" search. As you have it now, it's actually performing a "keyword" search with the <artist> field against the website, which works but has the potential of returning a lot of irrelevant stuff as well. Here is what I use to have Discogs use ONLY its artists category for the same search:
https://www.discogs.com/search/?type=all&artist=<Artist>
And here's a few of contributions of my own:
Metal Archives Artist search:
https://www.metal-archives.com/search?searchString=<Artist>&type=band_name
Metal Archives Artist + Title search:
https://www.metal-archives.com/search/advanced/searching/songs?songTitle=<Title>&bandName=<Artist>#songs
Spirit of Metal Artist search:
https://www.spirit-of-metal.com/liste_groupe.php?recherche_groupe=<Artist>
Here are two that I use that I haven't seen mentioned yet:
All Music (Artist)
http://www.allmusic.com/search/artists/<Artist>
All Music (Album)
http://www.allmusic.com/search/albums/<Album> <Album Artist>
Google Artist Pictures: https://www.google.com/search?tbm=isch&tbs=imgo:1,iar:s,itp:face&q=<Artist>
This one might be helpful in the ongoing search to replace the artist pictures that used to come from last.fm. I don't think that the "face" part is being used right now, and if it works as I believe it's supposed to, it might be helpful in weeding out superfluous results.
Anyone can help me for a weblink search for <Artist> - <Title>, and an other one for <Artist> - <Album> for searching covers on Deejay.de
Here you are... :)
Artist+Title:
https://www.deejay.de/$Lower($Replace(<Artist>+<Title>," ","+"))
Artist+Album:
https://www.deejay.de/$Lower($Replace(<Artist>+<Album>," ","+"))
The functions $Lower and $Replace are not mandatory, since the site would perform both changes by itself anyway.