In their most recent newsletter, Subterranean Press has announced that in the early stages of releasing a number of past Subterranean titles in electronic formats. Among the first readers can download are John Scalzi’s The God Engines (Kindle) and Robert McCammon’s Mister Slaughter (Kindle / Webscriptions).
If print editions are more to your liking, both the Scalzi and McCammon are still available as hardcovers.
Look for more Subterranean ebooks in the very near future.