List of all Installer Sources
From ModMyiFone - Wiki
Feel free to add to this list. I'm sure I'm missing a lot here.
AppTapp Official: repository.apptapp.com
Conceited Software: conceitedsoftware.com/iPhone / http://conceitedsoftware.com/iphone/beta
Ste Packaging: psmxy.org/iPhone-apps
Original Three
HighTymes: hightymes.org/iPhone/plist/index.xml
iSwitcher: web.mac.com/iswitcher2/list.xml
Loring Studios: loringstudios.com/iPhone-schnapps/index.xml
Others
AlliPodHax: ipodhackz.com/index.xml (Installs All Sources)
AlohaSoft: (Aqwoah theme available after donation)
Apogee LTD: apogeeltd.com
BigBoss: sleepers.net/iPhonerepo (Bigboss' apps, themes, scripts)
BigBoss Beta: sleepers.net/iPhonerepobeta (BigBoss' beta stuff)
Byooi Digicide: byooi.com/iPhone/digicide.plist (Jiggy Apps)
BlackWolf: m8an.de/ownrisk.xml (Use at your own risk. Extended Preferences)
Caissa: caissa.us (Caissa native chess)
CedSoft: prog.cedsoft.free.fr (iSnake/Bounce)
Code Genocide (Adults Only): repo.codegenocide.com (iSteamy)
CopyCoders: homepage.mac.com/hartsteins/copycoders/copycoders.xml (Network Apps)
Death to Design: iPhone.deathtodesign.com
Dlubbat: www.dlubbat.com/iphone.xml (TextTwist)
Earth3D: s.imov.eu (Earth3D 3D representation of the earth)
Fight Club: dezign999.com/repo
Gogosoft: www.blackblack.org/gogobeta.plist (NetChess)
iApp-a-Day: iappaday.com/install
iBlackjack: patrickmccarron.com/irepo
iJailbreak: ijailbreak.com/repo.plist
iPodTouchMaster: ipodtouchmaster.com/files/repo.xml (1.1.3/4 Jailbreak & iPhone Apps For 1.1.1/2/3/4)
iPhoneDevDocs: idevdocs.com/install
iPhoneSurge: iPhonesurge.com/installer.xml
iSolitaire: iPhone.rustyredwagon.com/repo
iSpazio Official: repo.ispazio.net
iThemes: imagine09.com/IndexAE.xml
iUnlock: i.unlock.no
Limited Edition iPhone: limitededitioniPhone.com/lei.xml
Marco Giorgini: marcogiorgini.com/iPhone/plist.xml (Yeti3D, Pac3D)
Mateo: bblk.net/iPhone (BeatPhone)
MNPlight: movenplay.gforge.inria.fr/iPhone (MoveNPlay Client, Manage iTunes, contacts and so forth)
Mobile Stacks: mobilestack.googlecode.com/svn/repository/internal.plist
Moyashi: hpcgi3.nifty.com/moyashi/ipodtouch/repository.cgi
MTL: home.mike.tl/iPhone
New Att iPhone: newattiPhone.com/repo.xml (Tetris, Penguin Panic)
Niffob: niffob.com/triPhone.xml (Themes and more)
Nuclear Design: nucleardesign.net/repository
PBF: polarbearfarm.com/repo (Showtime Video Recorder)
peeInMyPantz potty: potty.peeinmypantz.com (Guide to Singapore Public Transport)
Pyrofer's Projects: pyrofersprojects.com/repos/repos.xml
R4m0n: iPhone.r4m0n.net/repos (iPhysics)
Robota Softwarehouse: iPhone.robota.nl (Chess, Screenshot, iGo, iSpit, iLevel, Sysinfo)
scummVM: urbanfanatics.com/scummvm.xml
Shai's Apps: ride4.org/shai.xml (Customize Addons, and install over 70 sources)
ShopList: mazinger.cs.yale.edu/iPhone-apps/index.xml (ShopList)
Simek's Graphic: simek.ddl2.pl
SimPort: install.ifon.no (Import contacts directly off your SIM card to iPhone)
SNES: frankssnesroms.890m.com/REPO/snesroms.xml (SNES Emulator)
SoSsiPhone: rep.sosiPhone.com (ContactFlow)
SpoofApp: www.SpoofApp.com/source (CallerID Spoofing)
Studded: studded.net/installer/index.xml
Swell: lyndellwiggins.com/installer/Swell
Touch Fans: touchrepo.com/betarepo.xml
Touchmod Team: touchmods.net/rep.xml (Sip client for the iTouch)
weiPhone: app.weiPhone.com/installer (weTools/weDict)
Wizdom on Wheels: iPhoneapps.wizdomonwheels.com (Common website links)
Zodttd: zodttd.com/repo (Gameboy advance, openttd and psx4all)
From ModMyiFone - Wiki
Feel free to add to this list. I'm sure I'm missing a lot here.
AppTapp Official: repository.apptapp.com
Conceited Software: conceitedsoftware.com/iPhone / http://conceitedsoftware.com/iphone/beta
Ste Packaging: psmxy.org/iPhone-apps
Original Three
HighTymes: hightymes.org/iPhone/plist/index.xml
iSwitcher: web.mac.com/iswitcher2/list.xml
Loring Studios: loringstudios.com/iPhone-schnapps/index.xml
Others
AlliPodHax: ipodhackz.com/index.xml (Installs All Sources)
AlohaSoft: (Aqwoah theme available after donation)
Apogee LTD: apogeeltd.com
BigBoss: sleepers.net/iPhonerepo (Bigboss' apps, themes, scripts)
BigBoss Beta: sleepers.net/iPhonerepobeta (BigBoss' beta stuff)
Byooi Digicide: byooi.com/iPhone/digicide.plist (Jiggy Apps)
BlackWolf: m8an.de/ownrisk.xml (Use at your own risk. Extended Preferences)
Caissa: caissa.us (Caissa native chess)
CedSoft: prog.cedsoft.free.fr (iSnake/Bounce)
Code Genocide (Adults Only): repo.codegenocide.com (iSteamy)
CopyCoders: homepage.mac.com/hartsteins/copycoders/copycoders.xml (Network Apps)
Death to Design: iPhone.deathtodesign.com
Dlubbat: www.dlubbat.com/iphone.xml (TextTwist)
Earth3D: s.imov.eu (Earth3D 3D representation of the earth)
Fight Club: dezign999.com/repo
Gogosoft: www.blackblack.org/gogobeta.plist (NetChess)
iApp-a-Day: iappaday.com/install
iBlackjack: patrickmccarron.com/irepo
iJailbreak: ijailbreak.com/repo.plist
iPodTouchMaster: ipodtouchmaster.com/files/repo.xml (1.1.3/4 Jailbreak & iPhone Apps For 1.1.1/2/3/4)
iPhoneDevDocs: idevdocs.com/install
iPhoneSurge: iPhonesurge.com/installer.xml
iSolitaire: iPhone.rustyredwagon.com/repo
iSpazio Official: repo.ispazio.net
iThemes: imagine09.com/IndexAE.xml
iUnlock: i.unlock.no
Limited Edition iPhone: limitededitioniPhone.com/lei.xml
Marco Giorgini: marcogiorgini.com/iPhone/plist.xml (Yeti3D, Pac3D)
Mateo: bblk.net/iPhone (BeatPhone)
MNPlight: movenplay.gforge.inria.fr/iPhone (MoveNPlay Client, Manage iTunes, contacts and so forth)
Mobile Stacks: mobilestack.googlecode.com/svn/repository/internal.plist
Moyashi: hpcgi3.nifty.com/moyashi/ipodtouch/repository.cgi
MTL: home.mike.tl/iPhone
New Att iPhone: newattiPhone.com/repo.xml (Tetris, Penguin Panic)
Niffob: niffob.com/triPhone.xml (Themes and more)
Nuclear Design: nucleardesign.net/repository
PBF: polarbearfarm.com/repo (Showtime Video Recorder)
peeInMyPantz potty: potty.peeinmypantz.com (Guide to Singapore Public Transport)
Pyrofer's Projects: pyrofersprojects.com/repos/repos.xml
R4m0n: iPhone.r4m0n.net/repos (iPhysics)
Robota Softwarehouse: iPhone.robota.nl (Chess, Screenshot, iGo, iSpit, iLevel, Sysinfo)
scummVM: urbanfanatics.com/scummvm.xml
Shai's Apps: ride4.org/shai.xml (Customize Addons, and install over 70 sources)
ShopList: mazinger.cs.yale.edu/iPhone-apps/index.xml (ShopList)
Simek's Graphic: simek.ddl2.pl
SimPort: install.ifon.no (Import contacts directly off your SIM card to iPhone)
SNES: frankssnesroms.890m.com/REPO/snesroms.xml (SNES Emulator)
SoSsiPhone: rep.sosiPhone.com (ContactFlow)
SpoofApp: www.SpoofApp.com/source (CallerID Spoofing)
Studded: studded.net/installer/index.xml
Swell: lyndellwiggins.com/installer/Swell
Touch Fans: touchrepo.com/betarepo.xml
Touchmod Team: touchmods.net/rep.xml (Sip client for the iTouch)
weiPhone: app.weiPhone.com/installer (weTools/weDict)
Wizdom on Wheels: iPhoneapps.wizdomonwheels.com (Common website links)
Zodttd: zodttd.com/repo (Gameboy advance, openttd and psx4all)