There's lots of little things in the upcoming release of sqldev. Frank's post reminded me of one that I forgot to show at openworld. We have support for the same DVT Gauge component that he mentions in sqldev's next version. However, all you have to do is write a sql statement. It's really simple to use. For example, I took the free space report from Tom Kyte and added guages.
The only you'll need to do in sqldev is select the correct value and it'll turn it into a gauge. In the base sql, the percent used is
((kbytes_alloc-nvl(kbytes_free,0))/ kbytes_alloc)*100 pct_used " .
In order to make it more graphical I just changed it to this
'SQLDEV:GAUGE:0:100:0:0:'||((kbytes_alloc-nvl(kbytes_free,0))/ kbytes_alloc)*100 pct_used
The SQLDEV:GAUGE trigger the check for values. The first 2 numbers are the min and max values. The next 2 are the low and high values. Lastly, the current value to plot.