Proprietary

What I've shipped but decided against releasing the source code.

Pins for Pinboard (Free with IAP, iOS, macOS, Swift): A modern Pinboard app. Currently in active development. Follow its development on Twitter.

Pocket Quotes (iOS, Swift): Collect your favorite quotes from famous people, books, TV shows, etc. Currently in active development.

Writing Kit (iOS, Objective-C): Powerful text editor with advanced researching tools for bloggers and writers. Achieved 20,000+ paid downloads. Featured by Fast Company, Ars Technica, Macworld, etc. Also featured in books like Hand Held Hollywood’s Filmmaking with the iPad & iPhone and The Writer’s iPad.
Cyberspace (iOS, Objective-C): Productivity-focused web browser for iOS. Achieved 5,000+ paid downloads. Featured by Macworld, GigaOm, etc.
Eso (iOS, Objective-C): A very fast English-Vietnamese and Vietnamese-English pocket dictionary.

MPCS (iOS, Objective-C): Keep track of doctor appointments and treatment process for cancer patients at Miles Perret Cancer Services.

Pocket Tropes (iOS, Objective-C): Offline collection of movie/book plot conventions and plot devices on TVTropes.
Today (iOS, Objective-C, Ruby, Sinatra): Mobile client for BaoMoi, Vietnam’s most popular news aggregator.

eTest (iOS, Objective-C): English quiz app for learners.
Shopaholic (iOS, Objective-C): Mobile client for HotUKDeals website.
.Vn (iOS, Objective-C): Vietnamese keyboard implementation for iPhone.
LinkHay Reader (Web, Ruby, Sinatra): Minimal web reader for LinkHay, a popular reddit-style Vietnamese news aggregator.

Time Waster (iOS, Objective-C): View interesting photos, read articles, quotes, etc from various sources.
The Reader (iOS, Objective-C): eBook downloader and reader.
linkroom (Web, PHP, Kohana): Triage Twitter timeline by sending seemingly interesting links to read-later services and ignoring the rest.

My Setup (Free, Web): Collection of interviews with people from different industries about what they use to get their job done. Inspired by Uses This.
ngaunhien.me (Free, Web, PHP): Read funny comic strips on each page load. In Vietnamese, the name translates to “random”. Achieved 300,000+ visits.
jtale (Web, PHP, CakePHP): A manga-reader with user-contributed content.

Custom Smilies (Plugin, WordPress, PHP): Add emoticons to blog entries and comments. Achieved 10,000+ downloads and made Mashable’s 30+ plugins for WordPress comments and 300+ tools for running your WordPress blog lists.

Reg Assistant (Windows, AutoIt): Import and export Windows registry in one click. Achieved 10,000+ downloads.
Folder Tweaker (Windows, AutoIt): Customize background image and icon for folders in Windows Explorer. Achieved 20,000+ downloads.