What behavior have you had to implement in your Rails applications that you feel could exist nicely as a plugin?
What plugin functionality have you searched for in the past but couldn't find?
What existing Rails plugins could be improved or extended, and how?
I once wrote a component for an application that did uploaded a zip of photos to an application so they didn't have to be done one by one, I think I may make that into a plugin when I have time, well a new version of it, the code's a little ugly.
I'd like to see some sort of in-built video playback/streaming. I need it for my current project.
Not easy to answer. Everyone is biased towards his own current projects. Additionally a lot of great plugins already exists.
Personally I would like to see some menu plugin for a typical data base application. E.g. where there are few user roles, and every user role has different rights. And a main menu with sub menu which depends on user's rights to actions.
A (CSS) menu is reimplemented in almost every data base application. It is rather given application specific thing and I don't know how hard it would be to implement some general solution or template.
I'd like to see an engines plugin that dropped in an admin interface that provided a dashboard summary of all the models in the app, with configurable activity charts.
A Credit Card Payment System
Right now, no one bothers implementing credit card payments until a site has become "production quality". Single-person projects or small startups don't bother making this at first b/c they would much rather spend their time prototyping new, hard, or interesting features.
This is bad in the long-run for everyone, including end-users, b/c the default is to offer (often innovative and really great) services for free, which means only already-funded teams or people with lots of extra time can even get to the point of making something.
If this existed, were packaged up neatly, and were as dead-simple as Rails scaffolding, small projects could default to whatever payment scheme that actually made sense -- like pay-per-use, donations, trial periods, first 5 free, etc. -- making it possible to fund the really great products out there, instead of forcing them to rely on outside funding or ads, which ruins the product.
In a real physical store, people expect to pay. If the person on the other side of the counter gives me something for free (w/o buying anything at all), I say "Are you serious??" and walk away bewildered. But online, I almost expect it. This is bad! Because now everyone expects it, and people trying to make great things can't focus on actually doing that b/c they are too busy trying to figure out how to make it great and free.
Oftentimes, there are free things out there online that I like so much that I would like to pay for, but there's simply no easy way to do it. And I'm not alone. I use tipjoy and have donated to things that have a PayPal donation setup like Auditorium, but I don't see these as adequate.
The best thing out there that I've seen is RailsKits. But as far as I understand, they aren't packaged properly so that I can add them to my site whenever I please like a plugin or gem.
I agree with Greg... there are lots of great plugins, and lots of great ideas for more.
I think there's always a need for more web APIs to be supported. As we go forward with API driven services and semantic web, there's tons of work to be done on that front.
http://www.programmableweb.com/ is a great starting point for thinking about what really useful APIs don't have a rails plugin or ruby gem yet.
Cheers!
Walt