With Gecko Dialer, you can place a call, while reading the phone number in another app.
Similar to Facebook chatheads and other bubble launchers, Gecko Dialer provides you with a unique multitasking experience. You can use your dialer from any app on the device.
Kudos to the guys from Tooleap for their SDK that I used for creating the floating dialer window:
Use Gecko Dialer to see your recent calls, or use T9 search to browse through your contact list.