I recently found this graphics agency, SHCH Graphics Group, that specializes in rendering typographical forms into complicated flourishes, apparently by hand. They have a variety of examples of their work for major corporate clients, but also have examples of work they've done on napkins. I like their use of incredibly bold colors (mostly primaries, and reflex blue). Here's an example of a piece apparently for Nivea:
Their website has a lot of interesting pen work with a focus on fluid forms and fine lines. You can find the original site at sgr.kiev.ua. Unfortunately I know very little about them and stumbled across their work in my online travels. Here's another piece that incorporates thread (a common theme in their work) into the final layout.
Much of the work is in Cyrillic, as they appear to be in the Ukraine, so I'm unable to provide much more information about the finished pieces; on a purely aesthetic level, though, they are very pleasing. While the forms have a very tight and focused feel to them, I really appreciate that they are imperfect, for example, the arcs occasionally break or have small aberrations in the curve. The impression of handwork is retained, which is often lost in this style (which is commonly achieved with Illustrator or some similar illustration software, rather than a pen).
Be sure to check out their website, as there's quite a bit of work available to browse.