Yes, absolutely. I love everything by Gastr del Sol, and I have his solo albums Bad Timing and Eureka, both of which are excellent. I intend to pick up Insignificance too.
Also, I've heard that he's currently considered a permanent member of Sonic Youth.
Just about anything he's involved with is brilliant. A particular favorite of mine is the EP Halfway to a Threeway.
Ordering direct from Drag City is the cheapest way to fill in the gaps in your collection.