My memory pretty much sucks, but I can tell you some songs that Jon or both of them have got playing, singing, or writing credits for. I'm sure someone will correct me with any errors or supply the missing data.

Kiss the Bastards, Saints & Sinners (I think this was a writing credit with Jon & Dave Sabo, can't remember if there were vocals or not).
Hell Is Living without You, Alice Cooper
Yeah, Eddie Murphy (Jon and Richie both sing)
House of Cards, Rockhead
Soul's On Fire, I've Been Working Too Hard, Southside Johnny (Jon only, singing)
Rockin' Around the Christmas Tree, Darlene Love & Ronnie Spector (Jon plays guitar)
Jon sang background on a few songs on Billy Falcon's Pretty Blue World CD.