Photoshop :: Cracked Glass Effect

I am looking for a way to make a convincing cracked glass effect in Photoshop (CS3). Not broken (fragmented) glass, just cracked. It would, ultimately, be a layer over another graphic (a round gauge).

Ive googled many combinations of this and, while there are many tutorials that say they are for cracked glass, most are actually for broken glass, not cracked, and none of them, of either sort, are very convincing.

There are also any number of sites offering brushes; but again, the few that post examples arent very convincing, which leaves me leery of the rest.

I am open to suggestions, or if anyone knows of a tutorial site I may have missed . . .

BTW; I am much more of a technician than an actual artist, so my attempts at painting/drawing something have been, shall we say, less than adequate.