For quick little data-crunching programs like this, I really like the .NET languages, either C# or C++ .NET. The GUI builder makes it a snap to create simple dialogs with buttons and text fields and other standard widgets, and the .NET foundation classes make it easy to work with files, the network, and other system resources. Unfortunately the resulting programs are dependent on the user having the .NET runtime installed, which is a big drawback for me since it's just one more hoop people need to jump through. I prefer apps that are completely stand-alone.

I'm sure you could use Python or Java or something else to build a similar app just as quickly, but those would also be dependent on the user having some special runtime installed, and I don't have much experience with those languages.