I have some URLs like these:
http://plutov.by/post/cubique_zf_jquery
http://plutov.by/post/mysql_useful_queries
You can use something like this in your .htaccess:
RewriteRule ^post/(.*)$ post/main?title=$1 [L]
You should keep this rule BEFORE one entry point rewriting rules. If rule will trigger then rewrite rule lookup will be finished (since [L] option specified)
Some modification of paths may be required if you want to use these rules in VirtualHost context