Is it possible to create a custom entry for a different hosting site? I'm wanting to upload my pics to imgur.
Only if there is some kind of tool you can use to upload to them. (Some sites do have tools and shell extensions, but I don't know about imgur in particular.)
The Send To one should work in Opus.
I've installed the one you mentioned, and it indeed does work under Opus, in that it's added to the Sent To context menu. What I'm wondering is whether a third-part site can be added to Preferences > Photo Sharing, which can then automatically add the URLs to the clipboard, as the ImageShack tool does.
There's no way to do that in general, since each site does things in different ways.
If the site gives the uploaded files predictable URLs then it's easy enough to make a button which works out the path and puts it in the clipboard. On the other hand, but if the site mangles the filenames/paths in complex or unpredictable ways then it's something that the uploader tool would have to handle.
The generated URLs seem predictable enough imgur.com/GT3Ts
"GT3Ts" isn't very predictable unless that was the name of the file to start with...
Oh, I thought you meant the generated links on the right-hand side.