There are all types of photo apps out there. I usually use Picasa or Windows Live Photo Gallery. Then I upload pics to Flickr, but what do you use for pictures, and to share them with other people?
I use Picasa for general management. It's lightweight and quick. I use Photoshop CS3 for any heavy duty editing (anything more than cropping or rotating). I have photos spread all over the web. I have alot in my Picasa Web Albums account, but I mainly use that for uploading projects that I'm going to be sending/linking to friends since Picasa does a great job of batch uploading. All of my artistic photography I post to my deviantART profile. I recently opened a Flickr account for mobile uploads and easy connection to my Blogger account.
On my Mac I use iPhoto as a Photo management tool, and on Linux i use Picasa. To edit my Photos i also use iPhoto and sometimes GIMP both on Linux and Mac.
To edit photos I use adobe photoshop, its a very useful and powerful tool and a great artistic medium. As for sharing I used to be on flickr but now typically share on facebook with friends and family.
I'm actually using the new Picasa Beta 3 for Windows XP. I think it's a great piece of software available to download for using picture editing for the basic things. I can't wait until they take it off of beta for full release!