I'm mining a day or so on all the new currencies as they come out, just in case, although there seems little point in most of them. Doge is proving remarkably successful, as it seems to be the only one, oddly, given its peculiar origin, that has built up a community of apps, sites, trading, utilities and so on. It's the one I'm the most optimistic about, at this stage, even though it seems a meme-based currency should have short shelf-life. Probably helps that it wasn't pre-mined (as far as I can tell).