I've really been trying hard to get to grips with these mashup services we've been reviewing lately - Teqlo, Yahoo Pipes et al, but they just seem so high level at the moment. Dapper is among those that's slowly winning me over: it has proven useful for tricky little problems like aggregating social networks, tracking blog stats, aggregating video clips and the like (see the full list).
On Monday, Dapper is releasing another useful tool: Dapperfox is a Firefox extension that creates an RSS feed from any page - suggested uses include creating an RSS feed for your wall at Facebook or a feed for searches on YouTube.
There are web-based apps to do this, of course, but those have proven tricky: Feed43, for instance, requires some real brainpower to find the right piece of info on the page and get it working. DapperFox, meanwhile, seemed to work well for the suggested use cases. That said, some of the web-based apps may still be preferable if you only need this feature occasionally: Feedtier is now called Feedity, and it seemed to work great when I tested it today.