Got another query via Twitter today for a Yahoo Pipe that is oft requested – something that will aggregate a number of feeds and prefix the title of each with a slug identifying the appropriate source blog.
So here’s one possible way of doing that.
Firstly, I’m going to create a helper pipe that will truncate the feed from a specified pipe to include a particular number of items from the feed and then annotate the title with a slug of text that identifies the blog: (Advisory: Truncate and Prefix).
The next step is to build a “control panel”, a place where we list the feeds we want to aggregate, the number of items we want to truncate, and the slug text. I’m going to use a Google spreadsheet.
We can now create a second pipe (Advisory: Spreadsheet fed feed aggregator that will pull in the list of feeds as a CSV file from the spreadsheet, for each feed grab the feed contents, then truncate them and badge them as required using the helper pipe:
To keep things tidy, we can sort the posts so they appear in the traditional reverse chronological order.
PS Hmmm… it might be more useful to be able to limit the feed items by another criteria, such as all posts in the last two weeks? If so, this sort of helper pipe would do the trick (Advisory: Recent Posts and Prefix):
HTH:-)
OUseful.Info, the blog... 
In Pipes version 1 a pipe had to execute within 2 minutes. In Pipes version 2 this limit has been reduced to 30 seconds. This limits the number of urls (rows) in the spreadsheet.
An alternative approach I have used is to create a Google Reader bundle and then to do a lookup for each item to a Google spreadsheet. That’s obviously not efficient, since it requires a lookup per item instead of a lookup per feed.