It seems for the past few years I've been continually surprised by what can be accomplished with web applications. Gmail and Google Calendar showed me that I can fairly easily live without Outlook. Mint pulls together my financial data and lets me work with it in a responsive and well-designed interface. I've almost transitioned to solely using Google Docs to manage various personal text documents and spreadsheets. Flickr has allowed me store all my pictures online which makes it easier to share with friends and stores them in the cloud where I trust that Yahoo will do a better job backing them up then I would on my own computer.
And speaking of online photo management, I just heard about Picnik on the latest episode of Windows Weekly and, after trying it out briefly, I was very impressed. One aspect of using Flickr that's been a little cumbersome is that I generally need to use a desktop photo editing program (for me, Picasa) to do general touch ups, rotations, etc to my photos from the time I take them from the camera to when I upload them for permanent storage to Flickr. This leaves a duplicate copy in Picasa, and I go through and delete these pics from time to time - a little messy.
Although Flickr provides some basic editing and orientation features (which have really improved since I first started using the service and generally work well), if you want more control over your pictures and still want to stay in the cloud Picnik seems like an interesting choice. With it, you can upload pics from your computer, or you can open them from sites like Flickr or Picasa Web Albums, work with them, and them save them to your computer or back to an online service. Picnik doesn't seem to offer all the various adjustments that a good desktop photo editor can do, and it still might be too slow for some people if working on large, detailed photos, but I was very impressed by the performance and will try using it more for working with my simple personal pics.
This blog post sponsored by Picnik - "Photo editing made fun"