I have found LabVIEW to be an excellent compromise between flexibility and power. If it has a plug, LabVIEW can talk to it. I have made LabVIEW the hub of the Engheta Group Laboratory, and almost every piece of scientific equipment can be controlled through it. This allows amazing flexibility and small setup times due to code-sharing.
My largest project in LabVIEW was the Electric Tweezers. This involved collecting data on particle positions through real-time image processing of a microscope video feed. A layer of vector mathematics was used to calculate a set of electrode voltages. Finally, the software interfaced with custom electrical hardware to use these voltages to apply an electric field to the particles. In addition, it had a "simulation mode" that interfaced with a virtual physical system so that one could test various electrode configurations and particle species. Unlike most experiments, I considered this to be a product prototype and so I built in a lot of ease-of-use functionality too. In my opinion, it was more friendly than most scientific tools I have had my hands on.
I have also built a microwave near-field scanner that mapped electromagnetic fields. This program interfaced with several stepper motors which positioned a near-field probe. Data was collected through a vector network analyzer (VNA) and recorded for each position. The GUI would display phase animated maps of the field for the selected frequency, providing us with a direct comparison to simulation and theory.
I have also used LabVIEW to post-process impedance tube measurements with the VNA. This allowed us to see the results of an experiment immediately and identify measurements that needed to be retaken due to loose connections.
I used LabVIEW to program a volumetric ultrasound imager. A focused ultrasound transducer was raster scanned in a water tank over an object. At each point a pulse was output from a waveform generator and an oscilloscope was used to collect the reflected signal. By manipulating the received waveforms, we could develop a topographical image of various layers in the system. There was a lot of other unconventional functionality that are proprietary and unfortunately I'm not at liberty to show the system.
Additionally, I have used LabVIEW to track my location through Google Latitude, monitor electrodeposition techniques, test acoustic sensors, project a version of Tetris onto a building, perform green-screening in a photobooth for a party, and make a slide show that advances on the beat of a drum.