Querydsl is a framework that enables the construction of statically typed SQL-like queries. Instead of writing queries as inline strings or externalizing them into XML files, they can be constructed via a fluentDSL/API like Querydsl. It supports JPA, JDO, Java Collections, SQL via JDBC, Lucene, and Hibernate Search.
LampCMS is a Q&A Web site with best features of StackOverflow and Quora mashed together. It integrates with Twitter, Facebook, Tumblr, and the Blogger API, and can post questions and answers to all of these APIs. It is very fast and can handle millions of monthly visitors on a single inexpensive server.
selfoss is a multipurpose RSS reader, live stream, mashup, and aggregation Web application. You can register RSS feeds, and this Web-based PHP application will continuously fetch new RSS feed items. The items will be shown in a stream. You can also add other sources, like deviantart, Twitter, or tumblr users. Attaching new sources is very easy, and you can add any source you want (e.g. IMAP email account, log files, etc.). selfoss also allows you to collect all your postings on different communities (e.g. Twitter, your blog, etc.) and show it in one place. It features a Web-based RSS reader, universal aggregator, mobile support (Android, iOS, and iPad), and support for MySQL, SQLite, and MongoDB databases. It is easy extensible with an open plugin system (write your own data connectors). It is a lightweight PHP application taking up less than 2 MB.