Several things I think a computer should be able to do OOTB:
Raspbian comes with Netsurf and Midori, but neither one will log you into your Hotmail account. I've settled on Chromium as a compromise between performance and abilities.
Focuswriter works well for me. Forum reports are that the big office suites (LibreOffice, OpenOffice etc.) slow the Pi down terribly.
Raspbian already has Galculator, and I see no reason to change calculator programs. Gnumeric does as good a job on spreadsheets as anything I've ever used, and is available in the repos.
Music and Video Playing:
LXMusic fits in LXDE (the default window manager in Raspbian) of course, and plays MP3s with a very small resource demand and no real problems. It does have one bug, if it's set as default music player and you click on a music file, it opens the program but not the file you clicked on. XBMC will play music but as far as I can tell does not support playlists. However it's the only way to go to play video on a Raspberry Pi. You can use OMXPlayer, already built into Raspbian, but unless you call it directly from the command line (lots of typing!) you can't control it even to stop a video in the middle. XBMC does exactly that: controls OMXPlayer with its own GUI. Google Michael Gorven (Cocooncrash) to install it.
I find Synaptic handy; it has a search function. Installing things by apt-get is great if you know exactly what package you're looking for, but if you want a screenshot utility, Synaptic will help you find xfce4-screenshooter.
One more thing: if you use a full-size keyboard like I do, and you want the keypad to come on when the computer boots up, there is a tiny utility called numlockx to do that. Install that , and add this line to /home/pi/.bashrc: