Runs in your system tray. Right or left click the icon, or press Shift+Win+; (semicolon), to pull up a menu of categorized emoticons. Selecting an emoticon immediately copies it to your clipboard ヾ（＾ヮ＾)ﾉ
It's easy to code in your own emoticons (assuming you have Visual Studio). Look near the top of DesktopEmoticons.cs to see how the emoticons are added.
I realize I could have gone one step further and had this program read the emoticons from some kind of external text file or something, but... ¯\_(°⊱,°)_/¯ maybe I'll get to it someday.
Just want to download a ready-to-run copy of the program? Here it is: https://github.com/BenMakesGames/DesktopEmoticons/raw/master/DesktopEmoticons/bin/Release/DesktopEmoticons.exe
As the creator of this code, I am releasing whatever few copyright claims I may have over this code to the public domain. Any of the "tricky" bits in here were probably taken from MSDN documentation or Stack Overflow, anyway. Other than that, I wrote a class, and a function that turns a Dictionary into some MenuItems... so... whatever; don't care; public domain'd! Code is provided as-is, without warranty of any kind, etc!
Enjoy! :ﾟ｡⋆ฺ(*´◡`)