I like hashtables (and use them when I need quick 1-1 lookups), but for UI elements or other sequential-access type things, why not just keep the dataset/datatable around as long as you need it?

If you don't need really speedy data access and the dataset you have is small, you can even do a select/filter on the dataset to narrow the set you have without going back to the database.  OTOH, I found in a set of 10K records that it was much faster to ask the database to query and narrow for me than it was to use the dataset.

-Thor Johnson