What are some alternatives?
When comparing Key Remapper and SharpKeys, you can also consider the following products
Karabiner - Karabiner, previously called KeyRemap4MacBook, is a very powerful keyboard remapper for Mac OS X.
Microsoft keyboard layout creator - Edit the windows keyboard layout.
Key Manager - ATNSOFT Key Manager, Key Remapper, Text Paster
X-Mouse Button Control - XMouse Button Control (XMBC) allows you to create application and window specific profiles.
Ukelele - Ukelele is a Unicode Keyboard Layout Editor for Mac OS X.
KbdEdit - Keyboard layout editor, mapper/remapper.