Not without upgrading your account (to either a Premium paid account or a Prime or Illuminated "fee-enhanced Free" account). That being said, you don't usually need a separate database -- most third-party scripts will allow you to set a table prefix for the software that allows it to share a database with another package without collisions. (That is, two applications would normally use some of the same table names, but setting a prefix means that one would actually use "wiki_users" instead of "users".)