Multi channel Techwell 6805 video capture boards. They work great with Zoneminder software (supported by LML).

LML announces GNU/Linux H264 hardware (MG1264) codec (QCIF/CIF/D1) for real-time video applications: IP video streaming, conferencing, security monitoring/archiving. Tested with Linux Kernels 2.4 up to 2.6.31, GNU GPL driver.
Check this CIF sample stream