I've recently started using picasa.
I have used Thumbsplus for years for organising my pictures, but wanted something (preferably free) for my laptop.
After a little while I got the hang of how it works and have found it to be really nice. When it comes to putting them online, just select the ones I want (if I haven't already done so by putting them into an album) and press the button. Nice and simple.
To include the pictures in here, I just go into an online album, click on the thumbnail to see a larger version, then copy the image location.
The only thing I've found it to be not so good at is it's speed for indexing pictures. It's fine when I copy a memory card onto the laptop, but when I told it to include all (52k) pictures on my NAS it took several days and nights, before I got bored and stopped it.