rksoon, at the risk of breaking taboos, I enjoy the knife discussion right here, but also at the "other forum"
http://www.knifeforums.com
The crew over at JerzeeDevil
http://jerzeedevil.com/ seems a little rough at first but it is actually a great and welcoming group. They are all very passionate about knives, and some very thoughtful discussion goes on there. You'll recognize many of the regulars here over there too.
http://customknivesandguns.com/ is newer, but has a lot of good knowledge. Like here, many under-the-radar but respected makers are around, willing to discuss the nuts-and-bolts topics.
There are tons of maker-specific forums too, that range from active to crickets. For example, I like the forums at
http://spyderco.com/forums/ and
http://dozierknives.com/forum/
Finally, like JD and here, there are a lot of good discussions over at USN
http://usualsuspect.net/forums/, but registration is required.
I really think that you can gain a lot of knowledge from reading these forums and actively participating. Retail knife counters (like gun counters) can be either a great place to learn or a great place to hear all the BS you can handle.
This is a minority view, but I haven't been too impressed with the knife-related print resources available. The knife mags mostly strike me as thin, poorly written, and expensive, but
Tactical Knives magazine is one of the better ones (even if you're not especially into tacticals).
Knife shows (not "gun and knife shows", aka "gun shows with a few tables of Maxams") can be a great place to chat up a huge variety of experienced makers and collectors. I highly recommend making the effort to get to a good knife show.
When I was first getting back into knives, I ended up making a few "knife friends" here and elsewhere, and ended up getting together a few times for hikes or just a long afternoon in the garage looking at knives. I've met some really great guys. Look in the Community section here for local get-togethers.
But for the specific topics you mention (history, steel, design, locks, heat treatment, manufacturers, future trends), I think good ol' BF is the place to go.