Some weeks ago a tool got my attention - pgstats. It was mentioned in a blog post, so I tried it out and it made a very good first impression.
Now version 1.0 was released. It can be found in github.
It is a small tool to get statistics from postgres in intervals, just like with iostat, vmstat and other *stat tools. It has a number of modules to get these, for example for databases, tables, index usage and the like.
If you are running postgres, you definitely should take a look at it.