I have been using in my previous work busybox on a BlackFin.
we compiled perl + php for it, after changing s/fork/vfork/g it worked pretty good... more or less. Not having an MMU is not a good idea. The memory fragmentation will kill the server pretty easily. All I did was:
for i in `seq 1 100`; do wget http://black-fin-ip/test.php; done
It died while I was walking to my boss and telling him that the server is going to die in production :)
