One good solution I've found is Yahoo Pipes. Like a pipe on the command line you can feed it some input and it will pass the input to their engine, then create new output. In this case you can put in one or many feeds, apply filters (has words, doesn't have word, etc...) and get a new feed!
Input can be way more than just a feed; it can also be pages, CSV files, Flickr, Yahoo Searches, and more. They are working on Pipes v2 which will be even better.
Anyways, it looks like a very interesting and geeky way to manipulate content and get it just the way you want it.
Basic instructions:
- Get a Yahoo account
- Go to the Pipes page.
- Click the Create a new pipe link at the top of the page.
- Drag a Sources: Fetch Feed module to the grid.
- Add a URL (say http://content.dealnews.com/dealmac/rss/todays-edition.xml).
- Drag an Operators: Filter to the grid.
- Connect the dots between the URL and Filter.
- Fill in the filter with desired filter (like permit item.Title contains camera).
- Connect the dots between filter and Pipe output.
- Now click on the debugger and select Pipe Output and voila!
- Change the filter from Permit to Block camera, hit refresh in the debugger pane on the bottom, and you see all the feed items that do not contain camera.
- Save the pipe. Name it, and hit the Goto my pipes link. Click on the pipe you just saved and it will run. You will now have a new RSS feed!
There are many modules to play with, including a regex module to change the content. For example, add the feed source to the title of the item.
[crarko adds: I tested this, and it works as described. This was in the queue for a while and there may now be apps on the iPad that will do this. But I didn't know about Yahoo Pipes, and it looks like a pretty neat thing.]

