Oshi is a free JNA-based (native) operating system information library for Java. It doesn't require any additional native DLLs and aims to provide a cross-platform implementation to retrieve system information, such as version, memory, CPU, disk, etc.
Oshi is a very young project. We'd like you to contribute a *nix port. Read the project intro.
Here's sample test output:
Microsoft Windows 7
2 CPU(s):
Intel(R) Core(TM)2 Duo CPU T7300 @ 2.00GHz
Intel(R) Core(TM)2 Duo CPU T7300 @ 2.00GHz
Memory: 532.1 MB/2.0 GB