It depends on what you intend to do with your server. You might want to do opcode caching. By installing eAccelerator.

Standard recommendations would be:

Setting Description Recommended value
max_execution_time How many CPU-seconds a script can consume 30
max_input_time How long (seconds) a script can wait for input data 60
memory_limit How much memory (bytes) a script can consume before being killed 64M
output_buffering How much data (bytes) to buffer before sending out to the client 4096