Heh. I was the opposite -- a friend found out I was a Sluggy nut, and he recommended "A Hymn Before Battle" (the first Posleen book). :-)

That was over 10 years ago. I don't remember how long I'd been reading Sluggy before that, but it was a good while.

The fourth novel Hell's Faire includes some Sluggy Freelance guest strips by Pete Abrams since the popular internet comic strip is featured somewhat prominently in a way. (A massive armored military vehicle is named after Bun-Bun the mini-lop from the strip.) Some of the strips are samples of the actual comic strip and others are an exclusive alternate timeline setting where the Sluggy characters have to deal with the Posleen invasion.