Hi all! 
I hope this will not be treated as spam or something. Especially by all those who constantly try to find new sounds. Here is a couple of reliable places for your sample researches.
For those in hurry. A brief list of various places where you can easily obtain different types of sound content 
 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 or a candy shop. 
 http://www.philharmonia.co.uk/explore/sound_samples - sampled instruments of London Philharmonic Orchestra 
 https://www.lucidsamples.com - large amount (ca. 1GB) of free samples + good shop with electronic music dedicated sample packs 
 http://freemusicarchive.org/ whole free tunes/songs 
 http://sampleswap.org/filebrowser-new.p ... 2bb520dfa4 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
For those with time. You can spend hours browsing this forum, its topics and links to other forums: 
 https://www.kvraudio.com/forum/viewforum.php?f=42 - sample section of a great audio forum. Numerous topics with further lists.