Fetch

the data you need from one or many datasources in any data format.
Any popular SQL/NoSQL database
Popular APIs for social media and document storage
Parse HTML websites for structured data

Transform

the data to your desired format, adding whatever logic you need
JSON
XML/RSS
SQL queries against Excel/CSV
PDF
EDI
any custom format you want!

Communicate

your data via any communication channel or datasource with custom scheduling capabilities
Email/SMS/FTP/*
APIs/Social Media/DMS
Custom application dashboard for real-time looks at data

Recipes

Aggregated Activity Feed
Build endpoints against your social media activity feeds, order by time and create a dashboard with the aggregated feed
Aggregated Search Engine
Build search endpoints against public API|HTML search page, aggregate into a custom search engine
Twitter Bot
Run a database query every 10 minutes, when new data arrives tweet information
Data Collection via Forms
Build a POST endpoint saving data to your database, create an app with a form using this endpoint, build another app to view results
Generate a hosted .rss/.ics file
Scrape HTML, perform XPATH query to grab list of items, format using RSS/.ics and host at endpoint
Daily reports
Run SQL every n minutes, generate Excel spreadsheet and email to a distribution list
Auotmated invoicing
Once a month, execute a QB API call|DB query to determine outstanding billables, generate PDF invoice and distribute
Uptime detection
Perform HTTP request|DB query|API call every n minutes, send email if service is down
SLA
Perform HTTP request every minute, record status in db, create dashboard to graph uptime and calculate SLA
Continuous Integration
Create a POST endpoint which triggers a build, add endpoint to Github Hooks, return success|failure based on build result

Examples

eBook Search Engine - Aggregated search engine which searches multiple ebook databases for books
Movie Streaming Search Engine - Aggregated search engine which searches multiple movie search engines/websites for available movies
BirdieBot - Twitter bot tweeting every birdie or better on the PGATour
Wheel of Fortune Spin ID tracker - Twitter bot tweeting that night's SPIN ID, also has a sign up page for email notifications and ID history
Auto-generated AV Club TV Review RSS feeds - Stay current with the latest reviews for your favorite TV show. Find the show id based on the show's AVClub URL and pass it to http://www.datacombinator.com/api/avclub/feed.rss?id={{id}}. Here's the Game of Thrones (experts) reviews.
PGA Majors Calendar - Hosted .ics file for golf's four majors (and the Player's Championship)