Tools with alternatives, and my current favorite

Category Favorite tool Others that I've tried Reasons Disadvantages of my favorite Notes
Operating system GNU/Linux Windows Open source Harder to use A friend of mine who is not a computer guy uses Ubuntu with no probs
GNU/Linux distro Ubuntu Debian Popular, desktop-user oriented I don't like the upcoming Unity interface Debian is better for servers
Text editor emacs vi, Word, pico, nano, joe More features Default keybindings are really bad, though; use ergoemacs and viperre, "hacky"
Programming language python C, C++, Perl, Java, Haskell, Pascal, Basic, others Rather powerful, concise, readable, medium-sized, memory-managed Supposedly not as powerful as some other more functional languages; not as usable for small scripts as Perl I've never tried Lisp, and though I've tried Haskell and so far prefer Python, I haven't tried Haskell very much yet
Unix shell bash csh, zsh More featureful/shortcutty than csh; more developer momentum than zsh May switch to zsh once I learned it. Didn't like zsh's out-of-box completion behavior, but I assume there's a way to change that.
Python Web framework pyramid Django Python; more decoupled than Django Not as popular as Django
Scientific computing python scipy matlab, octave Open source sometimes you have to jump thru hoops to convert between lists and arrays, or to flatten and unflatten arrays
Version control (also called revision control)mercurial ("hg")cvs, svn decentralized, easy to use i liked darcs, but heard that it does not scale well; also, it is not as popular. heard that git has inelegant, hard to learn syntax
Remote mounting sshfs don't use it much right now due to some sort of timeout issue
Wiki Hatta Oddmuse, Mediawiki, usemod, a few others Mercurial backend Not very featureful Oddmuse is better for many use-cases
Computer Fujitsu T580Dell Inspiron 8000, Lenovo x61t, others
Webhost Nearly Free Speech
Virtual private server (VPS) host VpsVillage?cheap will prob. switch to linode or slicehost someday
Slideshow program qiv
Document preparation EasyLatex? (lightweight latex markup; a preprocessor for latex)Latex, Word Lightweight, power of latex, i like semantic markup unpopular (i wrote it)
Latex slide package Beamer seminar better maintained than seminar, also more featureful Annoying to make it do unordered lists indented in the usual way EasyLatex? supports Beamer
Graph visualization library graphviz
Machine learning framework Orange Weka it's python

Online tools

News website Nytimes, Economist one-page weekly summaries (they have a political and economic subsection)Various Free, the Economist is the only publication I know of that provides concise, comprehensive weekly summaries of the news I try to glance at Nytimes for domestic news that wouldn't be important enough for Economist to mention, or for breaking news that I should know about immediately, but then I get sucked in. I should spend less time reading Nytimes
Tech news website, Digg, Plastic, kuroshin, Hacker news, Reddit Reddit is also good for programming stuff, but worse for general computer news; Hacker news prime is good, but too much traffic; Digg is poor, plastic and kuroshin miss a lot of interesting tech stories; i love slashdot, but it's way too much traffic; if you only look at it a few times a month, you'll miss a lot; there's no way to get only the "top ten stories of the month ". If you read /., Only read /. comments if the issue is really important to you, since it takes a lot of time to read them; and don't trust them too much
Calendaring website Easy to use, Android widget available
Smartphone OS Android

Tools to know about (for which there are no popular alternatives, at least in my domain)

Remote login ssh
File transfer scp
Remote windowing X windows (scp -X)
Synchronization unison
GNU coreutils (do "info coreutils")
search through files grep, ack-grep