Props to hashcrack.blogspot.com for compiling the most comprehensive wordlist downloads on the web. Copying links here just in case blogspot ever blows up. Additionally head over to skullsecurity.org they have some specialized wordlists from various sources including the hacked RockYou database and a skim of Facebook names/usernames for a total of 14,488,929 distinct passwords to be exact, collected from 32,943,045 users.

HashKiller
InsidePro
APassCracker
Openwall
ftp.ox.ac.uk
GDataOnline
Cerias.Purdue
Outpost9
VulnerabilityAssessment
PacketStormSecurity
ai.uga.edu-moby
cotse1
cotse2
VXChaos
Wikipedia-wordlist-Sraveau
CrackLib-words
SkullSecurity
Rapidshare-Wordlist.rar
Packetstorm_dic_john_1337
Megaupload-birthdates.rar
Megaupload-default-001.rar
Megaupload-BIG-WPA-LIST-1.rar
Megaupload-BIG-WPA-LIST-2.rar
Megaupload-BIG-WPA-LIST-3.rar
WPA-PSK-WORDLIST-40-MB-rar
WPA-PSK-WORDLIST-2-107-MB-rar
Article7
Rapidshare-Bender-ILLIST
Milw0rm
Rohitab
DualisaNoob
Naxxatoe-dict-total-new-unsorted
DiabloHorn-wordlists-sorted
Bright-Shadows
MIT.edu/~ecprice
NeutronSite
ArtofHacking
CS.Princeton
Spacebar
textfiles-suzybatari2
labs.mininova-wordmatch
BellSouthpwp
Doz.org.uk
ics.uci.edu/~kay
inf.unideb.hu/~jeszy
openDS
sslmit.unibo.it/~dsmiraglio
informatik.uni-leipzig-vn_words.zip
cis.hut.fi
Wordlist.sf.cz
john.cs.olemiss.edu/~sbs
Void.Cyberpunk
CoyoteCult
aima.eecs.berkeley.edu
andre.facadecomputer
aurora.rg.iupui.edu/~schadow
cs.bilkent.edu.tr/~ccelik
broncgeeks.billings.k12.mt.us/vlong
IHTeam
Leetupload-Word Lists
Offensive-Security WPA Rainbow Tables Password List
depositfiles/1z1ipsqi3
MD5Decrypter/Passwords
depositfiles/qdcs7nv7x
ftp.fu-berlin.de
Rapidshare.com/Wordlist.rar
Rapidshare.com/Password.zip
Megaupload/V0X4Y9NE
Megaupload/0UAUNNGT
Megaupload/1UA8QMCN
md5.Hamaney/happybirthdaytoeq.txt
sites.Google.com/ReusableSec
Megaupload.com/SNK18CU0
Hotfile.com/Wordlists-20031009-iso.zip
Rapidshare.com/Wordlist_do_h4tinho.zip
Rapidshare.com/pass50.rar
sweon.net/wordlists
Skullsecurity.org/fbdata.torrent

Leetupload.com/WordLists
Passwords: to0l-base, zmetex, mrdel2000

Rapidshare.com/BIG_PASSWORD_LIST.rar
Pass:bodyslamer@warezshares.com

Rapidshare.com/dictionaries-vince213333.part01.rar
Rapidshare.com/dictionaries-vince213333.part02.rar
Rapidshare.com/dictionaries-vince213333.part03.rar

Rapidshare.com/Wordlist_Compilation.part1.rar
Rapidshare.com/Wordlist_Compilation.part2.rar
Rapidshare.com/Wordlist_Compilation.part3.rar
Rapidshare.com/Wordlist_Compilation.part4.rar

Rapidshare.com-word.lst.s.u.john.s.u.200.part01.rar
Rapidshare.com-word.lst.s.u.john.s.u.200.part02.rar
Rapidshare.com-word.lst.s.u.john.s.u.200.part03.rar

Rapidshare-Purehates_word_list.part1.rar
Rapidshare-Purehates_word_list.part2.rar
Rapidshare-Purehates_word_list.part3.rar
Rapidshare-Purehates_word_list.part4.rar
Rapidshare-Purehates_word_list.part5.rar

Rapidshare-_Xploitz_-_Master_Password_Collection.part1.rar
Rapidshare-_Xploitz_-_Master_Password_Collection.part2.rar
Rapidshare-_Xploitz_-_Master_Password_Collection.part3.rar
Rapidshare-_Xploitz_-_Master_Password_Collection.part4.rar
Rapidshare-_Xploitz_-_Master_Password_Collection.part5.rarr
Rapidshare-_Xploitz_-_Master_Password_Collection.part6.rarr
Rapidshare-_Xploitz_-_Master_Password_Collection.part7.rar
Pass: http://forums.remote-exploit.org/

Rapidshare-_Xploitz_-_PASSWORD_DVD.part01.rar
Rapidshare-_Xploitz_-_PASSWORD_DVD.part02.rar
Rapidshare-_Xploitz_-_PASSWORD_DVD.part03.rar
Rapidshare-_Xploitz_-_PASSWORD_DVD.part04.rar
Rapidshare-_Xploitz_-_PASSWORD_DVD.part05.rar
Rapidshare-_Xploitz_-_PASSWORD_DVD.part06.rar
Rapidshare-_Xploitz_-_PASSWORD_DVD.part07.rar
Pass: http://forums.remote-exploit.org/