Button Combos
More System Information
- Go to XMB
[Settings] > [System] > [System Information] - Press simultaneously
+ 
+ 
+ 
for a few seconds - Release those buttons then immediately press
and keep it held - While holding , press once to have the menu stay up on it's own.
Note: More information: More System Information
QA
Getting the QA Flag Menu
Set your cursor on (not in) Network Settings and press the key combo (all at the same time):
+ 
+ 
+ 
+ 
+ 
You should see Edy Viewer, Debug Settings, and Install Package Files if done correctly.
Note: Requires QA-Flag enabled in EEPROM. More information: QA Flagging
Shop
Unlock Demonstration Mode
Note:
Set your cursor on (not in) Security Settings and press the key combo (all at the same time):
+ + 
+ 
Note: Requires unlock code afterwards. More information: Unlock Codes
Web browser
Unlock browser debug settings
Open the browser then press simultaneously the combo:
+ + + + 
+ +
+ 
It's a little bit difficult combo, but has interesting features like UI Settings > Motion type: 1 that enables coverflow for tabs.
- Thanks to Luca93xD for sharing it's findings
PS2 Netemu
Unlock Configuration Mode and Debug Information Mode
Note:
Inside a PS2 game, access the ps2netemu menu by pressing 
and press the key combo (all at the same time) for a few seconds:
+ + + 
then press 
for two new options in netemu: Debug Information and Configuration.
- Credits to picard for his awesome RE skills
