LauncherPro or ADW Launcher for your launcher
Swype for your keyboard
Applanet, which is a Black Market app, so you can get every app for free.
Last.fm
Pandora
Winamp
gTabSiMiClock for your clock widget
TweetDeck for your Twitter and Facebook updates
Rom Gripper for if you want to use Emulators, you can directly download roms with this
Ringdroid for if you want to use music as a ringtone
Dolphin Browser for your web browser
Astro for your file browser
Advanced Task Killer
GameBoid - GBA Emu
GBCoid - GB/C Emu
Gebsoid - Genesis Emu
Nesoid - NES Emu
SNesoid - SNES Emu
Barcode Scanner to scan barcodes for apps from the internet