Important MySQL startup options

back_log	Change if you do a lot of new connections.
thread_cache_size	Change if you do a lot of new connections.
key_buffer_size	Pool for index pages; Can be made very big
bdb_cache_size	Record and key cache used by BDB tables.
table_cache	Change if you have many tables or simultaneous connections
delay_key_write	Set if you need to buffer all key writes
log_slow_queries	Find queries that takes a lot of time
max_heap_table_size	Used with GROUP BY
sort_buffer	Used with ORDER BY and GROUP BY
myisam_sort_buffer_size	Used with REPAIR TABLE
join_buffer_size	When doing a join without keys