samer wrote• Terminal - a must have for the geeks. *
*: requires jailbreak.
There is an app called "Rove Mobile Admin" and it offers SSH, Telnet and RDP (MS Remote Desktop) clients, it's available for free from the App Store (hence no Jailbreak needed).
But if you want to SSH to 127.0.0.1 then yeah I think you need to jailbreak your phone and enable the SSH server.
BTW Firemint Real Racing GTI 2010 is a great racing game.
I also recomment abaia (chess game)
Photoshop Express for rotating pictures, adding effects, etc
"Remote" to control iTunes over Wifi.
Fring for MSN chat and voice calls
Cycorder (from cydia) for those with a device that does not support movie capture natively. (like the iPhone 3G)
Also, for those who dont have ios 4 can still get some sort of multitasking by installing "Backgrounder" from cydia. Note that if you want wifi to stay on even when the phone is on standby, you'll also need to get "Insomnia"
SBSettings lets you manage basic phone settings in a very convenient and quick way... also from cydia.
All these are free, but some are "lite" or "demo" version... still good to have though.
As paying app.. I would like to get G60-Camera Gear.