LINQPad is amazing. I have a full licence and have persuaded a couple of companies to buy site licences before.

It's would be great if there was some kind of full version trial so people could try it with full intellisense and package manager support.

Yeah, LINQPad is great! I use it for so many weird cases, everything from rather complex scraping with phantomjs to trying out things like regexs. I've saved small scripts that make it easier to get into new projects, such as making lists of files that have been changed the most and people who have the most commits etc.. Really recommend it for .NET devs.

There are good F/OSS versions of LinqPad - see Arnova CShell and RoslynPad.