I used KA-Blam for 1 run and I hated them (I'm probably in the minority, sorry!). I thought the quality wasn't as good, and the crease where the books were folded, the printing was cracked. (A good printer avoids this, as cracked spines lower the value of books) The color of the print was not true and it took a long time to get my books. Was not impressed.
I use http://www.ReadyComics.com, they have great bulk deals, delivery to cons they attend for free, UV coat covers with no extra charge. They send you proofs too. Any problems I've had they have remedied very quickly, with no fuss. They also are partnered with Diamond distributors, the only major comics distributor out there. Our local comic shop won't sell indies unless they have a diamond number, so having my books printed here had a HUGE advantage for me. They also do metal prints, buttons, stickers, posters and vinyl banners.
I use http://thinkpro.net for t-shirts, bags, and stickers. Of all the places I've purchased stickers, this place was hands down the cheapest for really high quality UV coated glossy stickers. They also do vinyl decals and do prints, but I've never tried those services.
I use http://wackybuttons.com for buttons. The quality is nice and they are super duper crazy fast. I can almost wait until the last minute to get buttons made. They are fairly inexpensive and they save your order forever so its easy to reorder more. They also do magnets too, but I haven't tried it yet. (I want to)