Cannot boot into recovery (Samsung Galaxy S)
I also had a boot loop today, after flashing Semaphore's ClockworkMod Recovery according to these instructions, then trying to boot to recovery mode. What helped me out was the hint at the bottom of that page: to use Replicant's recovery.img instead:

heimdall flash --KERNEL recovery.img --no-reboot


Update: Note that the hint has now been removed with the comment:


  Using a non-Gingerbread-compatible recovery for initial install will result in lost IMEI.