#1 Data cache

[Ben]

Implement a data cache that cuts down database lookups.
This could cache data in the middle tier when it is
selected. If ther data is not in the cache, it's
selected from the database, and stored in the middle
tier. If there are any updates (DB writes) the entire
cache can be flushed.

May be issues with large amount of data in the middle
tier - so most recent access should be stored, with
older items dropped out of the bottom of the cache.