I love, love, love this program! Xobni is a free add-on to Outlook and makes finding past emails oh-so much easier than searching via Outlook directly. It sits quietly on the sidelines until I need it and springs into action with no wait time. It has already indexed my emails in the background (didn’t notice any slowing during this!) and I can quickly see at a glance the conversations I’ve had with someone or what I sent/received on a certain date.
If you use Outlook, this is definitely worth a look!
Xobni: Email organization, search, and navigation for your Outlook inbox