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.
TinyIB is a lightweight PHP image board which emulates the functionality of 4chan. If you use MySQL or SQLite, you can use it to create an efficient setup able to handle large amounts of traffic. If you don't use a database, it can store posts as text files for a portable setup capable of running on virtually any PHP host.