Freesound.org provides a large number of free quality sound files. In order to download sound files from this web site, you have to register. The files are free for non-commercial use according to the web site.
Car alarm: http://www.freesound.org/samplesViewSingle.php?id=53840
Police Siren: http://www.freesound.org/samplesViewSingle.php?id=62878
Car horn: http://www.freesound.org/samplesViewSingle.php?id=54086
Arming car alarm: http://www.freesound.org/samplesViewSingle.php?id=29723
Thunder storm http://www.freesound.org/samplesViewSingle.php?id=17075
Dragon http://www.freesound.org/samplesViewSingle.php?id=66642
Dinosaur: http://www.freesound.org/samplesViewSingle.php?id=15026
Dinosaur footstep http://www.freesound.org/samplesViewSingle.php?id=77027
Forest http://www.freesound.org/samplesViewSingle.php?id=18765
Heart beat: http://www.freesound.org/samplesViewSingle.php?id=21409
Drum http://www.freesound.org/samplesViewSingle.php?id=84221
Sword http://www.freesound.org/samplesViewSingle.php?id=65380
Heavy wind http://www.freesound.org/samplesViewSingle.php?id=16796
Base drum http://www.freesound.org/samplesViewSingle.php?id=30668
Drum beat http://www.freesound.org/samplesViewSingle.php?id=40849
Ocean http://www.freesound.org/samplesViewSingle.php?id=13564
Cell phone http://www.freesound.org/samplesViewSingle.php?id=30054
Glass breaking http://www.freesound.org/samplesViewSingle.php?id=59263
Cat http://www.freesound.org/samplesViewSingle.php?id=4915
Dog http://www.freesound.org/samplesViewSingle.php?id=24965
Mockingbird http://www.freesound.org/samplesViewSingle.php?id=1055
Grasshopper http://www.freesound.org/samplesViewSingle.php?id=58240
Gun http://www.freesound.org/samplesViewSingle.php?id=37236
Beer cap opening http://www.freesound.org/samplesViewSingle.php?id=32264
Champagne opening http://www.freesound.org/samplesViewSingle.php?id=71837
Guitar http://www.freesound.org/samplesViewSingle.php?id=1374
Ghost http://www.freesound.org/samplesViewSingle.php?id=6598
Rooster http://www.freesound.org/samplesViewSingle.php?id=43382
Ice cream van http://www.freesound.org/samplesViewSingle.php?id=24609
Composite alarm http://www.freesound.org/samplesViewSingle.php?id=25032
You can search sound files by keywords at freesound.org.