If you're frequently uploading videos and photos to Flickr, YouTube, Vimeo, Twitpic or Facebook, you know that it's slightly annoying to have to log into each service, search your files and go through their uploader. Courier solves all this for you.
It's a desktop app that lets you make Envelopes that represent various services, so you can set Vimeo and YouTube as a "videos" upload, and Facebook and Twitter and Twitpic as a "photos" upload, for example. Or just mix and match whatever you like. Once you've set the Envelopes, just drag your media onto those envelopes, and Courier will automatically upload your files for you without having to visit their web pages.
There've been Flickr uploaders and YouTube uploaders and FTP clients before, but as far as I know, nothing's combined all these various services into one app. Realmac also incorporated extensibility, so other services can add uploadability after the fact. For example, there is an Amazon S3 plugin that you can use to back up your files to the cloud.
As far as I've seen, it handles file uploads quite well, except when there's a slight problem with, say, tags. I tried uploading a 100MB YouTube video that seemed like it was successful, until Courier told me 10 minutes later that one of the tags had a bad character in it. I had to reupload the video with better tags, which was successful. It would have been nice to figure out if the tags worked or not before the upload failed, but that is most likely a limitation with YouTube rather than a Courier thing.
In any case, if you're a frequent uploader, Courier is for you. [Realmac]