Once you start to have hundreds of custom controls (thanks to people like Prabhakant Patil for making libraries like this one) the task of finding the best candidate for your user interface grows impractical the way the control palette and search works today. It should be possible to flatten the palette hierarchy and browse by type, name..even rating could be an option.
Let's say that I need a boolean. Now instead of digging into all the sub-palettes to see the different booleans there I simply want all my boolean controls to show up as thumbnails that I can browse through. I can add a search phrase as well to limit the results to controls with a certain phrase...However as I seldom decide the name myself I would also want to be able to easily tag controls with my own description and use that to search it later on.
The interface could be very similar to the glyph browing functionality we have in the VI Icon Editor. You can select a category, filter by name, see previews of the glypsh that match the criteria etc, but the experience should be closer to what you have available in picture organizers. Resizable window etc. A very crude example (based on the mentioned glyph browser):
An alternative or addition to this would be to include a preview in the operative system. This way if you browse a folder where you have lots of LabVIEW controls you could see them as pictures instead of anonymous files.