Here are my essential iPad apps for the System Administrator.  Replacing my preferred RDP and SSH apps from my iPhone apps.

App: Mocha VNC

Platform: iPad and iPhone
Cost: $5.99

I love this app as a VNC viewer, controls anything running a VNC server.  It also has WOL capabilities if you're on the same network.  However, make sure your IOS device has a good password, as this app does not provide any additional security.

App: Remote Desktop - RDP

Platform: iPad and iPhone
Cost: $5.99

If VNC is not your thing, then this Remote Desktop app will fit the bill.  I love the ability of having a list of my servers to just click on and connect.  However, make sure your IOS device has a good password, as this app does not provide any additional security.

App: ADHelpDesk

Platform: iPad and iPhone
Cost: $4.99

This app handles the basics of AD user management.  It can reset passwords and unlock user accounts.  And for under $5, it saves from having to initial an RDP session and launch ADUC.  This app will require you to authenticate to the domain on each launch.

App: Prompt

Platform: iPad and iPhone
Cost: $4.99

All you need for SSH terminal goodness.  This app does it all, use keys, save passwords, can perform an initial command (like screen -r) on connection, and has in-app auto-completes.  It also has a custom on screen keyboard with tab and arrow keys on top.  Add to this it's ability to password protect the app, and you, like me, will find it lacking nothing.

App: P. Whisperer