All of the above is excellent advice on custom controls in LabVIEW.
National Instruments also has an Application Note located here, <a
href="http://zone.ni.com/devzone/conceptd.nsf/webmain/A9FBCAA7A3D7922186256A3000652B56">LabVIEW
Custom Controls, Indicators, and Type Definitions</a>. Check this out
for more information about creating your own custom controls.
In terms of finding custom controls already created, do a Google
search. You should be able to find quite a few websites that have
custom controls for free. It's just a matter of finding the one that
fits your needs.