Purely by accident, I've hit upon a great mulch for outdoor potted plants - orchid "soil," which is a coarse mix of bark and composted "forest products," as the Miracle-Gro people call it, with a small amount of polymer moisture retainer and a very mild A/P fertilizer added. Looks great, particularly on the more purely decorative plants (coleus, scented geraniums, ornametal sweet potatoes, and such)) but more importantly, keeps the soil evenly moist. I've used a couple of different brands this season; I prefer Miracle-Gro so far. The difference in the performance of my tomatoes is astounding. Not a hint of blossom end rot anywhere.
Also, this stuff is making the first effort at real urban gardening by the ol' Customary Dining Companion a roaring success. After a good start with a Genovese basil last year that survived until this spring (!), he now has another giant plant of the same strain, along with a French thyme, a rosemary, a bay laurel, and four tomato plants (three Roma, one Red Pear) that are approaching hedge-like proportions, acquired for the princely sum of 25 cents each at the Evanston farmers market. The lessened maintenance made possible by the orchid mix has been a big part of his thriving brood, and he's jazzed to know that the bay laurel could become a full-fledged member of the family with virtually no effort on his part.
It's admittedly a bit expensive to use on a really large scale, but I do plan to use some of the leftovers on my peonies and iris in the front garden next week, after the upcoming manure/bone meal/dried blood top-dressing. Also, while I realize dogs will eat pretty much anything, I doubt that a mouthful of bark shards will hold much allure.