Need help with personal knowledge management!

http://journler.com/features/full/index.php, for me. Mac-only, but it might give you an idea of what's possible.

I got a lot of great advice in response to my similar question here: http://ask.metafilter.com/96294/Info-wrangling

I don't know if this helps, but I've used almost all of the tools you mention. I've come to terms with nothing being all encompassing, and making do while keeping an eye out for something substantively better. For a couple years I used http://www.atlassian.com/software/confluence/ extensively for my personal wiki, but these days, I find more and more of my day-to-day notes goes into Evernote. There are a lot of things I wish were better, but the combination of good indexing, network syncing and decent native clients makes it the first thing I reach for now. I pay for Evernote Premium which supports SSL syncing and arbitrary file-type attachments. The biggest weakness at the moment is lack of good sharing options. As far as Firefox extensions, I've used Scrapbook for certain tasks, but mostly I use http://www.zotero.org/ for web-page saving. The academic citation support actually comes in incredibly handy for remembering when something was saved. You might want to give that a try. I continue to use Delicious, but honestly it really frustrates me. It was great a few years ago, but it just hasn't evolved. It doesn't save a copy of the bookmark, there's no way to organize collections or add notes, and since it defaults to public, it just makes all kinds of personal bookmarking really inconvenient. If Zotero 2's network syncing works well, I may end up switching completely off Delicious. For RSS, I make liberal use of Google Reader's starring, although I've admittedly never had much luck later finding stuff. Organizing papers and presentations is still on my TODO list. Zotero has support for PDFs, but I haven't used that much since ideally I'd like to have it available in multiple locations... I've started attaching them in Evernote, but if anyone else has a system they like better, I'm all ears.

I switched from Tiddlywiki to Evernote. Evernote is much faster and makes it easier to include screen shots and random documents, plus it's accessible from my Mac, PC, and iPhone. I store my domain names and site configurations in Evernote, so I think your firewall notes should work fine there. Interesting PDFs that I might need in my business go into Evernote or into my tidy folder system on the Mac. I've increasingly been using Spotlight notes to help me find PDFs; I don't know if there's an equivalent on Windows. For RSS feeds, I've been happy with NetNewsWire. I use the Mac desktop version and the iPhone app. It's easy to save an item in the NetNewsWire clippings file, but I'm more likely to copy & paste relevant snippets into Evernote. For example, if one blogger says something that could inspire my own blog post, I put a snippet and link to their post in Evernote with the tag "blogideas." When it's time to write a post, I look at everything tagged "blogideas" and get inspired. I don't use bookmarks anymore except for sites I access regularly, and those are synced with Foxmarks. For most other sites, I stick a quick description and link in Evernote.

Another vote for http://evernote.com, which I use on my iPhone, on two Macs at home, and at work through the web interface. I'm also a Premium subscriber, and the file attachment feature that lhl mentions is very useful. I'm also a heavy user of the 'email to Evernote' option as a way to quickly get content into the system. On the Mac, the Evernote client adds an option to the print dialog that allows you to create a PDF and import it into Evernote in one step. It took me a while to start trusting the system -- i.e., not keeping the same or similar content in another system -- but now that I've really started to make use of Evernote's features I'm very happy with it.

Another vote for Evernote. I've tried to store all information on the cloud (e.g. via Google Doc), but turned to be not that fast and convenient. I've also tried to store information locally (via personal wiki, or structured folders, or knowledge management software), but the portability turned to be a big problem. Now Evernote provides the ultimate solution. I setup it both in my laptop at work (XP) and my mac at home, also in my portable disk. Then the information are accessible everywhere easily. Even I'm with a totally stranger's computer, the web version still works. Even I don't have a computer, the mobile version still works on the phone. Evernote gives the perfect concept of sync everywhere. I do love it and feel thankful for its provider.

The security environment of my job prevents me from letting proprietary information outside of our network. Can Evernote be used entirely locally? Meaning no data gets sent to outside servers?

I'm going to put in another plea for you to consider Zotero, as it fits most of your requirements. I'm testing the 1.5 Sync preview version, and it seems pretty stable. It allows you to use NetDav to synchronise on the server of your choice (as well as Zotero's server). It also allows you to do 'standalone' notes, which means you could implement your own version of GTD on it.

@jpdoane. Of course, you can use Evernote as a local app.