tsort. There we go. I don't hate tsort. pbcopy and pbpaste.
Edited to add: Git. Git is also a thing of beauty. Who knew revision control could be made to not suck? Sure, SVN was a welcome relief from the unrelenting stone faced hell that was CVS, but that's damning by faint praise.
I love git, and use it for all of my projects. But my love for git might also be because I have spent so much time on learning it.
ed went on to influence ex, which in turn spawned vi. The non-interactive Unix command grep was inspired by a common special uses of qed and later ed, where the command g/re/p means globally search for the regular expression re and print the lines containing it. The Unix stream editor, sed implemented many of the scripting features of qed that were not supported by ed on Unix; sed, in turn, influenced the design of the programming language AWK, which in turn inspired aspects of Perl.
And I love AWK too.
I like and use grep. But, as a programmer, I like ack much better than grep.
Ask me what git merge does, or how to branch, or even how to delete a file in a repository (w/o deleting it from your local), or how to revert back to another version, or how to even check out, and I'll say I dunno. I read the documentation, but am still confused. I sometimes feel like I'm dumb because I feel everyone loves git and everyone gets it. Glad to hear that I'm not alone.
I'm not an iPad user but it makes a lot of people pretty happy.
Chrome is usually a pleasure to use. Firefox used to be that way, and they are starting to regain my trust again. I feel good about using Firebug as well.
Skype has some irritations, but for the most part it's still marvelous to open up a video chat to fucking Zanzibar whenever I feel like it.
vim is not always easy, but wow is it rock solid.
Upgrading Debian works very well for me at least, thanks to the miracle of apt-get. Debian itself, well, it's not winning usability awards, but still....
And don't even get me started about C the language. It makes me want to go find Ritchie and punch him in the junk.
Why is rsync not a binary linked to a useful librsync? Why STILL TO THIS DAY a grep/egrep difference? And why did Apple integrate Interface Builder -- their best piece of software, IMO -- into Xcode?
Let's not even get into Google.
Games, a game delivery system like steam or perhaps vlc for playing my favorite music, but even then, its the music that makes me happy, not the program playing it...
Ont he other hand, there is a lot of software that I actually hate.
The list of software that I actively despise, however, is finite, but unbounded.