I’ve been using GuruNet for over eight months. It’s a handy Windows utility that lets me alt-click on a word on my screen to get a dictionary lookup, web search, translations, and book search. I found a competing product today called Zapper. It takes context into account (as does GuruNet) and activates with a control + right click. I suppose I could install that too and do a head to head battle. Zapper has more specific lookup options, like shopping, sports, and finance, but I’m sure GuruNet can easily add more if they so desire.