As far as the underground and subculture, 2600 and phrack were good in the late 90's, but a shift happened. I'll try and summarize, but I don't know the timeline and groups perfectly, other folks please correct me where needed.

In the late 90's, shit started getting real. Two of the gnarliest groups at the time were ADM, and TESO. They were formidable and highly skilled; it was rumored that ADM had backdoored a large majority of the DNS nameservers on the Internet, and TESO made public the first ever remote security hole in the previously invincible OpenBSD. I think somewhere around that time is when people besides hackers started taking hacking seriously, because alot of hackers were able to get dayjobs doing their thing.

This didn't sit well with other 'purist' hackers, and they made their distaste known to the community. This was the birth of the 'whitehat vs. blackhat' fight, and where the 'hacker underground' turned into the 'anti-sec movement'. The manifestation of this that I am most familiar with was the Phrack High Council (pHC). Basically they were mad that their friends sold out. They declared war on all White Hats, called it "pr0jekt m4yh3m", and started attacking them. Hell, they even re-wrote the now famous "Hacker Manifesto". They went nuts for a while, you can see archives of their mayhem and the zine they ran here. If I remember right, they were putting them out parallel to the last few issues of the original Phrack. Other blackhat groups that joined the war were b4b0, Brotherhood of Warez, and h0n0.

They made waves. They even attacked ADM and TESO, but it couldn't last forever. One of the pHC guys, a young kid named g4y h1tl3r (no lie) committed suicide (I can't find articles, but I've seen lots of refrences to it). He was around 15 years old at the time. Also, about that time (early 2000's) was about when hacking became a really, really viable way to make some quick, dirty money. Botnets and clickfraud, carding, etc. I think that when that happened, hacking went from 'social outcast hobby' to 'illegal enterprise', and law enforcement started to get serious about it. The pHC leader was a dude named Stephen Watt, who went by the alias JimJones. He got sentenced recently for his part in the huge TJX hack that happened back in '06. While he says he never profited off his hacking activity, he was associated with the scene, and the only endgame for that is eventual jailtime, especially with all the new heat from the government.

So pHC started to quiet down, and soon after them, a few new groups arose. The ones I know of are dikline, who apparently backdoored official Ruby repositories; 2l8, who took an EFNet server hostage for a day (much lulz); geist, who I don't know much about, but they get shout-outs from my personal favorite: zf0. I looves me some zf0. Those guys are like an evolved pHC. I'm pretty sure there's some membership carry-over, but zf0 publications are well written, and their anti-sec rants are very well reasoned and thought-out.

Plus they're scary. I'm sure you recognize the name Dan Kaminsky. He's the security researcher that found a flaw in the DNS protocol and proclaimed the sky was about to fall. What he found was correct, but how he went about publicizing it was in bad taste, according to the zf0 guys. So they pwned the ever-loving shit out of the poor guy. They hit very high-profile White Hat targets: BinRev, Lemos, Kevin Mitnick. They hit people that annoy them: 4chan's Anonymous. They hit old school hacker heroes that are no longer 'active': cDc, even 2600.

So yeah, 2600 and phrack were good back when. But the underground has changed.

Edit: wall of text. Is there a format equivalent for <p>?

2nd Edit: some of my atrocious grammar