Carbon
Carbon is a light-weight component model and services framework providing enterprise quality services.

Excalibur
Excalibur is an open source software project of The Apache Software Foundation that contains a lightweight, embeddable Inversion of Control container named Fortress that is written in java.

Gravity
Gravity is a dependency and configuration management framework that allows multiple forms of configuration via a plugin model with a primary focus on the Dependency Injection / Inversion of Control (IoC) design pattern. The framework comes with a default BeanShell plugin for configuring the components.

HiveMind
The concept behind HiveMind, and most other dependency-injection microkernels, is to reduce the amount of code in your application and at the same time, make your application more testable. If your applications are like my applications, there is an awful lot of code in place that deals just with creating objects and hooking them together, and reading and processing configuration files.

JICE
JICE is an XML-based tool for constructing and configuring Java applications. It consists of: JIC Language - an XML format for representing the configuration of Java instances in a Java application. JIC Engine - A factory that constructs graphs of Java instances based on the instructions in an XML file.

NanoContainer
NanoContainer is a Dependency Injection (DI) container that manages trees of PicoContainers.

Peapod
Peapod is a lightweight container. There are a number of such projects and products out in the wild, and "container" has been applied to a wide range of offerings. Simply put, Peapod lets you take a plain Java class, an interface and a small fragment of XML metadata and hand off responsibility to a host.

PicoContainer
PicoContainer is a lightweight embeddable container for components that honour Dependency Injection.

Soto
Soto is a lightweight, non intrusive service framework relying on a powerful configuration format based on Java's introspection capabilities. The framework implements neat ideas such as conditional instantiation, resource resolving and layers. It comes with JMX and AOP functionality.