From ModMyi - Wiki

Look here for the most up-to-date Installer 4 sources in alphabetical order.
Remember to always be careful when using these sources,
we take no responsibility for what you do with them.
To add these to Installer, check out this guide.
Do not post links to warez.

Community Sources

BigBoss's: apptapp.thebigboss.org/repofiles/installer4/
ModMyI: i.modmyi.com
RiP Dev: i.ripdev.com
Ste Packaging: repo.smxy.org/installer4/
iPhone-notes.de: i.iphone-storage.de/
iSpazio Official: repo.neolinus.org/ispazio/

All of The Others

A27 Dev: a27dev.com/installer/repo
M2: m2.iponeall.org
4pp13: http://123Locker.com (Only supports firmwares before 2.1; They use a Cydia repo now)
iModZone: i.imodzone.net
srtDesign Labs i.srt10coupe.de/
Club iFone: www.clubifone.org/repo/
Club iFone: www.clubifone.com/repo/
HHVN: iphone.handheld.com.vn/installer
Hack My iPhone: hackmyiphone.info/installer/
Hiphonepro: hiphonepro.com/repo/
ModElit3ge: elit3ge.info/repo/
Tavvy: hackmyiphone.info/Tavvy/
The App Place: applace.co.cc/repo/
ZoddTTD: zodttd.com/repo
Hackint0sh: hackint0sh.org/repo/
iClarified: installer.iClarified.com
iFon 2.0+: installer.ifon.no
iModZone: imodzone.exroverthost.com/repo/
iSpazio Official: repo.neolinus.org/ispazio/
Imagine09 (Themes): www.imagine09.com/repo/ (This is a Cydia repo)

Languages

gPDA.ru (Russian (in English)): gpda.ru/r

Handheld Viet Nam (Vietnamese): iphone.handheld.com.vn/installer