Here's a quick and easy way to send files from your PC straight to your Wii. Sendelf is a new Wii homebrew program from henke37 that sends files over TCP from Windows computers to the Wii. Here's the programmer's description of the program:

Usage instructions

1. Start the server on the Wii, that is start either the standalone server or the Homebrew channel
2. Unzip and run
3. Select file to send
4. Enter the IP address of the Wii
5. Make sure that the correct protocol is selected
6. Change the port if needed (most likely from using the client for the other protocol previously)
* The standalone server uses port 8080
* The Homebrew Channel uses port 4299
7. Enter any arguments if needed
8. Hit the send button

Or just double click on an elf or dol file, it will be sent directly to the last used IP address. No, it does not crash if you hasn't set the IP address yet.
Full feature list

* Works with both the standalone server and the Homebrew channel
* Works with both elf and DOL files
* Saves the used settings in the Windows registry so that you don't need to change them at each start
* Is extremely tiny, partly thanks to the release being UPX packed, but also from directly using the Win32 API
* Supports drag and drop of files onto the main window.
* Does basic sanity checks to prevent the most obvious user errors like forgetting to select a file.