Here's one for conservative Lightroom users like me. The real buffs, who are at home in all the blogs, in Adobe's exchange site for LR-plugins, etc., have undoubtedly known this for a long time. And if you don't use Lightroom at all, this is abracadabra--but please come back to my blog next time!
For the few of us then, one of the very few nagging discomforts about LR2 is that there is no way to control the watermark you add to the photo upon export: it sits in the left corner, in a fixed font and size. Of course you can go to Photoshop or use external small applications (shareware or freeware!) to add textual or graphic watermarks to jpg-files after exporting, but that is too much of a hassle: we want more elegant, user-friendly solutions. And finally I found one--as the real buffs know since a long time. One Timothy Armes developed a plug-in for LR that lets you add watermarks but also borders and frames in one go while doing the export! The watermarks can be text, self-written or taken from the photo's metadata, or graphic, and you can control the font (in a somewhat awkward way, for Mac-users at least, but it works) and where it is placed. Once installed and once you have designed your watermark, it will be used automatically for all exports, unless you turn it off again: 'fire and forget', really easy!
The multipurpose plug-in is called LR2/Mogrify and can be found in the Photographer's Toolbox; a Dutch-language, extended explanation was published in April 2009 (I'm really behind!) in DigitaleFotografieTips. The plug-in is 'donationware' and I guess that after a little more testing, I am going to make a donation to Mr Armes indeed: it seems to be worth more than whatever is a reasonable donation.
I felt, then, as if there were millions of beautiful penguins out in the sea of Plug-In and I just caught one nicely on my camera--just like the penguins in the Noorderdierenpark in Emmen (NL). And yes, if you look closely, there is a different watermark, in the right-hand corner, and somewhat less obtrusive than the standard LR2 one.
I also tried Mr Armes's LR2/Blog export plug-in; the entry on Berlin that I made earlier today, was made with it. But that one I found not useful: it may make it easy to upload a photo and add a little bit of text in a single go upon exporting from LR. However, you can only make simple unformatted text and also you cannot control the lay out of the photo in the blog entry. That was too limited to me, but if it's enough for you, have another look at the Photographer's Toolbox site.