Lately I've seen myself following a trend of putting more and more work in online tools. I've had an online linkdump for ages now, but since Sitebar integrated in Firefox it's serious. Furthermore, I switched from various standalone RSS aggregators to Bloglines, a free online service.
Besides these two key services, I've got a GMail account [still gladly using my own mailserver besides], an Orkut account [OK, I'm not seriously using that one], I use a small script written by myself to read some mailings online, I'm designing various CMS'es for my sites [this blog, my aquariusoft.org site] and I'm using various other ones [like the one on morphix.org.
In other words: my world is centered around my browser. I'm using a good and stable one, thank $DEITY, equipped with various extensions, including some for my peace of mind. But it remains only one program. If it crashes, I seriously loose work, for various things. Of course it's nice to have your environment with you whereever you go/work [that's exactly the reason it's happening this way for me], but it's interesting to watch the convergence.
I realized I missed some services. These replace actual hardcopy items for me, so they fall in a slightly different category, but here they are: wikipedia - an awsome online encyclopedia, dictionary.com - a handy online English dictionary and acronymfinder - nice to have in the world of abbreviations