As on many forums out there such topic exists, I allowed myself to create similar one here too. Many of you might be looking for an inspiration. Each of these sites grants the license. Mostly its CC or similar. Most of these samples are free tu use in commercial projects. Cheers!

At first, I'd like to share few non-obvious links:

http://www.soundbible.com - the title tells it all
http://www.freesound.org - a large repository of free (Creative Commons mainly) sounds. Sometimes weird, sometimes amazing. It's like a treasure chest
http://www.philharmonia.co.uk/explore/sound_samples - sampled instruments of London Philharmonic Orchestra
http://www.lucidsamples.com - large amount (ca. 1GB) of free samples + good shop with electronic music dedicated sample packs
https://www.kvraudio.com/forum/viewforum.php?f=42 - sample section of a great audio forum. Numerous topics with further list
http://freemusicarchive.org/ whole free tunes/songs
http://sampleswap.org/filebrowser-new.php?sid=ce21df4fd4b4a66258c1da2bb520dfa4 another sample repository
https://samplefocus.com/ - pretty new, but already nice online sample library. Right now it is free, you can upload new and download existing samples there

I think that is it for now as far as I can remember. What are your sources of samples?