The current plugin features might be ok for a very small company - but larger companies will need more options.  I will list a few features that I have used on the most well-used Magento shipping plugin.  I use shipping to Australia that splits over 10,000 zip codes into about 6 different zones, I end up with about 1600 shipping records just for that country.

- Listing multiple countries in one record, comma-separated instead of having to create a separate record for each individual country
e.g. country:   'CA,AT,BE,DK,DE,FI,IE,IT,LV,LU,MT,NL,NO,PT,SI,ES,SE,CH'  ( it could be the same for region / state )
- Zip Range
e.g.  2 x fields:  ZipFrom  and ZipTo ,  
for one zip code it would be ZipFrom:1000, ZipTo:1000
for a zip range it would be ZipFrom:1000, ZipTo:1598
for all zip codes it would be ZipFrom:*, ZipTo:*

- weight breaking formula.  So many carriers will round up to the nearest increment
e.g.  baseCharge: 5 , chargePerN: 1.2 , weightBreak: 0.50, weightBreakOver:0  
if the weight is 700g then it would be 5 + ( 1.2 x 2 ) << you would use Ceil to round up 700g to nearest 500g - 1kg , which is 2 x the weight break .

Thanks a lot for suggestions, we will consider adding them in the future versions.