SDLX is a translation tool with translation memory (like) functionality and a user-friendly interface. SDLX has been a rough ride in the past but I must admit that it is now both stable and pleasant to work with. SDLX is slightly better than common solutions like Trados TagEditor because you see the full sentence and not an insane segmentation of short sentences over several tokens/TUs caused by the formatting of the text. You can download a free trial version of SDLx lite from their website.

As of 2009 SDLX is a part of the SDL Trados Studio, which is an excellent collection of tools for the professional translator.