I've done similar work you've mentioned with it. Also edit papers with OpenOffice or Google Docs (Powerpoints in gdocs since oo's powerpoint app is smushed)

I've also installed gnuplot though I've yet to use it. Xournal is another great app, I use it to annotate PDFs I have to read or when doing a literature review.

The N900 is also great as a usb drive. I save my work to it when on university computers and sync it with rsync to my other computers (which then syncs it to dropbox). I run Window apps off the N900's storage so I can take advantage of bigger screens to annotate Pdfs with xournal or any other useful window apps that can be run off a flash drive.

lastly I've used the N900 (and before that the N800 for presentations). no, not the video output though I've been wanting to give a presentation off my N900 doing that. but as a slideshow remote (bluemaemo, vnc, or any other control method), or to have my notes on there.