I went through about 6 or 7 different FireFox extensions before I found one that did what it said it would do and worked consistently and didn’t make me jump through hoops to upload or above a photo.
I settled on simple but powerful Firefox add-on to use with Flickr for photo management. Fireflix.
It works as a sidebar- so when you install in order to access it you need to go to view->sidebar . Took about 30 seconds to set up with my Flickr account.
One of the things I loved most about the add-on is when surfing I can drag images to the sidebar and upload in batches to my Flickr account.
I found Fireflix to work very fast and a breeze to use. I think it is one of the best Firefox extensions available to use with Flickr and I have tried quite a few.
I have also used Picnik to edit and then send to Flick but this saves a step if image requires no editing.
A word of caution about using Flickr in your blog. When you upload an image an give it a “title” in the wordpress image upload, you are giving it alt tags. From an SEO point of view these are important- they can be used for keywords. Think of them as anchor text for images. When using Flickr you are in effect linking out to Flickr with keywords instead using those keywords to pint your own site.
For this reason i would avoid using Flickr as your primary source and host for your images. Whenever possible host your own images.
Wordpress image uploader and manager is AWFUL – especially the new flash version in wordpress 2.5 so it is tempting to got to a third party host.
A hassle- but I host my own images AND upload some of them to Flickr as well using Flickr for the social media advantages rather than as my image host.
As far as I know I have not seen a similar add-on to use with Internet Explorer. If you know f one let me know and I will post.