I started using the i-Clickr PowerPoint Remote iPhone App for my presentations recently. I like this app as it shows me the current (or next slide), annations and previous/next buttons:
And when you turn your iPhone you can draw on the screen, place check signs etc.
In short: I like this app (sorry if I am sounding like a commercial).
It has one drawback though: it needs a WiFi connection and you don’t always have one when presenting (or it’s unstable like eh.. somewhere).
The i-Clickr PC Control Application has a Direct Wireless options for this. It’s supposed to create a peer to peer connection between the iPhone and your pc but it doesn’t seem to work on the Windows 7 and iPhone combination.
I found a simple solution though: enable the Personal Hotspot option and connect your PC to it:
Now i-Clickr will find detect your PC using the Bonjour service: