Yahoo! Pipes has been hailed as the first Big Idea of the year and a breakthrough for mashups. It is well-deserved. That said, there are some limitations that need to be addressed.

1. First-Class Atom Support

I have read people talking about using Atom in Pipes, but I have yet to make it work reliably or see it in good examples. (Comment below if you know of some.)

2. Other Output Formats

As for output options, RSS and JSON are a great start, but it shouldn’t end there.

- Output to Atom 1.0

Broken record here, but seriously, this should have been done for Day 1. Vote for this at the Pipes Suggestion Board.

- Output to URL

I have already cooked up several scenarios that needed to end with a URL, for example. Awesome+1 if a Pipe could take in various parameters via form or URL, do all the internal processing in whatever sources and filters need be done, and then do a HTTP redirect to the resulting URL. You could do cheap authentication, Atom Publishing Protocol tie-ins, link tracking, in-line analysis, auto-populated Grazr widgets, or a million workflow-ish things this way. Vote for this at the Pipes Suggestion Board.

- Output to Text

I’d like a Pipe that can output arbitrary text that I build up from pipe metadata. Oh, for example: Document.writeln(). Think about that for a minute, and suddenly all sorts of new options open up: Script tags that reference a pipe to build HTML output on the fly, used inline on a webpage. Or how about building up an OPML file on the fly, or some other XML format, or…, or… Vote for this at the Pipes Suggestion Board.

3. Parameterized Item Content

I put together a little Pipe called “MyEatery” that takes a location and returns a feed of restaurants in the area, sorted by user rating thanks to Yahoo! Local. The problem is: each item is just a link to Yahoo Local, without any useful content inside the description. I have access to all kinds of nifty metadata from the Local results, but no way to push them up into the RSS item descriptions.

This one is the brass ring in my book: Pipes desperately needs a way to build the a description of each item using fields pulled from the various annotations with some static HTML. Something like:

${Title} (${Phone}) has been reviewed ${Rating.TotalRatings} times for an average rating of ${Rating.AverageRating}. The latest reviewer had this to say: {$Rating.LastReviewIntro}.

This would make Pipes a truely killer app in all sorts of new arenas. Being able to mix & mash the metadata into item content is a must-have. Vote for this at the Pipes Suggestion Board.