>Corporate Shadowfiles by Nigel D. Findley
This one depends on your tastes. I read it when I was just a juvenile offender, and it had a lot of background on how corps work, et al. So quite useful in that regard, although given your background, it may not be a huge help. Most of the gameplay information (like which division is part of which organization) is out of date or integrated into other materials.
>Fields of Fire by Tom Dowd
This really focuses on mercenary operations. It's SR2, so it plays nicely with SR3. Plus lots of pictures and Shadowtalk. However, many of the equipment roles have been subsumed by new materials in SR 3/4/5.
>Neo-Anarchists: The Guide to North America edited by Tom Dowd
I actually really liked this one. Dowd chose a few different cites and drafted up some nice data on them. The section on DC is pretty solid and I've been wanting to run there for ages. It doesn't go into a huge amount of detail; about what you get on Seattle in the main book.
>Neo-Anarchists : Guide to Real Life by Nigel D. Findley
This one goes a lot into living in the Shadowrun universe. I don't remember the details. Pretty sure the more useful parts of thsi book have been pulled into newer ones. I can't remember the last time I went back to look up anything in this one.
>Native American Nations Volume 1 by Nigel D. Findley
>Native American Nations Volume 2 by Nigel D. Findley
These two are pretty rough. They're two entire volumes based on the most ridiculous conceits in the setting (that there were scads of Native Americas hiding in the wings who have re-established their culture basically overnight). Fair bit of silly mysticism and such. As I never had any interest in playing that region, and the whole background is crazy, I couldn't stomach them.
>Seattle Sourcebook by Boy F. Petersen Jr.
Solid, but yeah, repackaged three times now? I'd hold off for a better quality reprint.
>Shadowbeat by Paul R. Hume
WHOO!!! Rock and roll! This book is a little crazy, but also a little underwhelming. There's all sorts of rules on holding concerts and reporting news. Unfortunately, not all of them make sense, and there's really not a lot on topics like snorting coke off of hookers or anything. I am hesitant to say it, but in many ways, this made rockers boring

Still, it's the only book where you can find costs for a synthesizer I know of.
>Shadowrun 2050 by Catalyst Game Labs
It's a reskin of SR4 in the setting of SR2. However, you already play SR2, so I don't know why you'd want this.
>Tir Nanog by Carl Sargent and Mark Gascione
>Tir Tairngire by Nigel D. Findley
Flipped through them, never read them, can't help too much. However, Trollman and Ancient History wrote an interesting review of them (the topic: Failed Game Design) which I found worth my time. Link redacted, since I don't want to cross any forum rules, but you can google it.
>The Universal Brotherhood by Nigel D. Findley
Great reading, generally considered the best SR adventure ever. Haven't run it yet, but I plan to. Still, if you don't plan on running UB, it may not get a lot of use.