I LOVE LinqPad. I cannot imagine to live without it anmyore.
You are new to c# development? Get it right away. It will help you learn c# and spped up your learning curve A LOT.
At first i was not sure what to do with it and thought "Why should i use an extra tool to test linq expressions?"
But meanwhile i learned that LinqPad is the perfect playground for rapid code developing.
I do a lot of method development directly in linqpad and just copy the code into my application when the result looks like i want. No waiting till the whole app is build. Get immediate response to your changes.