I've wanted (I think*) something like this on Windows for awhile: a client that syncs with Simplenote. I actually like the look of Simple Software Notes better (after all, simpler is better), but I can't use it at work because it doesn't include proxy support whereas ResophNotes does.
* I say think because I'd had Resophnotes for awhile, but hadn't used it because I wasn't sure I wanted any personal information synchronised on my work machine - I try to keep personal info off it as much as possible. But then I found out there was a portable version of Resophnotes so I've given that a whirl. But I guess then I need to think about encrypting my USB drive. And also, 15MB seems overkill for something as 'simple' as simplenote. So I might just return to using the web interface as a desktop app via Chrome. Oh decisions!