I agree that both Loose Fur albums are essential. I actually think O'Rourke's entire solo catalog is essential as well. Though my favorites would be Eureka and Halfway to Threeway, Insignificance is a terrific album. Ultimately, I feel I am probably more of an O'Rourke fan than a Tweedy fan. I was rather unimpressed with Tweedy until he started working with Jim. I've heard that O'Rourke did a mix of Sky Blue Sky that was scrapped. I'd be VERY interested to hear that.
I can't believe I am the only one to put this album on any list. This album is severely underrated in my opinion. It is WAY better than Wilco's Sky Blue Sky (also IMO). If you like what Jim O'Rourke and Glenn Kotche have brought to Wilco (i.e. YHF and A Ghost is Born), you'll love this. If you are also a fan of Jim O'Rourke's solo efforts, this is can't miss stuff!