SnapMeasure (together with BetterHandles) is being redeveloped as part of VectorScribe Designer by Astute Graphics, who acquired Nineblock last year. So far so good: there are some enhancements and at least one removed feature (scaling), but it does look as though Astute are committed to future development.

http://www.astutegraphics.com/products/vectorscribe/designer.html

SnapMeasure represents not only a massive improvement on Illustrator's native measure tool (no more peering in the info palette to see results, no more guessing when the cursor is just over a path) but it adds a raft of incredibly useful features which you can turn on or off as needed: readouts for radius at any point along a curve, measurement along a path, path direction. You can even measure to scale in a wide choice of units. The developers have been kind enough to implement (and improve on) some of my suggestions, so to that extent I am an interested party, but I'm connected in no other way to Nineblock: just a very satisfied user who would now find Illustrator unuseable without their products.