If your Excel model uses real-time data (stock market feeds, instrumentation add-ins) and you are not at your PC, it is helpful to have Excel alert you if an important condition occurs. Using the popular Growl tool, you can send an alert to your cellphone or have it popup on another PC.

To connect to Growl, you'll need to install the free Growl-for-Excel AddIn (growlforexcel.leftek.com). Then use a simple formula to send the alert when a condition occurs:

=GrowlIf(B5 > 10, "Price has been exceeded")