Well, you can always do some research on who he is, who to contact in his town and call the cops.
Just be prepared with URLs and proof that he is selling your stuff and that you want to press charges for theft.
That's the tricky part. For example: I published most of the content he now flaunts in 1984-1989 via a semi-monthly gaming fanzine called The Sorcerer's Scrolls. At least one of the modules he publishes in one of his compilations is mine, but it's from an issue of TSS I no longer own, and the original files (which were on an old 386 PC that died in 1993) are lost. I know it's my work, but demonstrating that isn't so easy. Other works are more problematic: Aberdan's Folly module was originally a four-part serial solitaire for T&T published in 1987 in TSS. When Shipman contacted me in 2003ish about reprinting old TSS articles I gave him permission to restore/edit Aberdan's Folly in a new format, and did not ask for compensation; as far as I was concerned in 2003 there was no money to be made and Jim's operation looked more like a T&T fan project. The final product was very nice, the guy who edited did a great job, and I thought the art was amazing. Of course cut to a few years later, and I find out the art was mostly pirated (the cover chiefly).
I got my first foreshadowing of problems in 2007 when I found out by accident that he had published "Nymph-o-Mania" and the module in question without my permission, nor did he send me free copies (as had been my arrangement for Aberdan's Folly). In fact in a prior engagement with him he had purchased most of my old copies of TSS issues he did not have, and I had indicated that if he was interested in reprinting my written content (about 30% of TSS's content was written by me) I could make similar arrangements as we had with Aberdan's Folly. The problem was, he went ahead and did that without actually consulting me. He may have other works of mine in books I don't know about. I know of at least one satirical article I wrote that I have been told made it in to a product....but none of these subsequent reprints were vetted by or agreed to. Had he simply asked, I would have let him do it for no cost other than some free copies; that's how these articles appeared in the 80's, and how I mistakenly thought his operation was working at the time.
When I confronted him about publishing Nymph-o-Mania and other works he was basically apologetic and sent me copies. I concluded with reservations that maybe there had been a misunderstanding, so I let it lie at the time....until....
After the explosion of reveals about his theft of art and content that popped up when he went live on rpgnow in late 2007 early 2008, I realized that something else had been going on with Jim and it was not just another fan-centered effort to keep T&T alive like the old days as I remembered it. I emailed him and asked that he stop producing and selling my content during the explosion of theft reveals, and tried to get some sort of explanation out of him, but he would not offer up any info, merely agreeing to stop selling my works. He did stop for a while, but with a recent check he has reneged on that agreement, clearly.
One side note: I never determined if it was him or an auspicious do-gooder, but one of my own books at the time was hit by a takedown request (Keepers of Lingusia, an OSR book for use with C&C and AD&D). The tie-in was that the same setting us used in all of my old T&T content, and the original "Keepers" title linked to my first T&T sourcebook I published in 1987. I got the book back up after demonstrating my copyright ownership, but it was intensely annoying...I never did determine if the accuser was Shipman trying to steal my work or a well-meaning soul who saw Shipman's sale of my book on his site and assumed it was more of Shipman's theft. After the email conversation I had with him, he did stop selling physical copies of books I had produced on his site (new issues of TSS, the Keepers book and my Troll Companion book, iirc). So he at least seems to have honored that portion of my request....though I wouldn't be surprised at all to find he was simply reproducing the work with names changes slightly.
So the conundrum I face is: would I have enough impetus and "damages" to make the issue worthwhile? Is police involvement for my sake alone worth it?* Groups have been formed among those wronged to discuss exactly this. I've sort of fallen out of the direction they went, but mostly I think the efforts have been to police his antics and try to get takedowns of his sites when possible.
*Would police take this seriously, too? I may be jaded about our police system but I am sure I don't have the legal know-how to navigate our system of justice to insure that this would work as intended. I'd be a lot more comfortable with a civil court situation, but even then I think the cost of pursuing it would outweigh any claims of damages. But again....my situation is pretty unique. Others have experienced real and significant losses because of his actions, including publishers like Flying Buffalo and Fiery Dragon. Why they haven't taken action, I don't know....