What else for code reusability

[Gambit_NI]

my task is to analyse our current systems and source code to identify potential areas that could benefit from either reusuable code, self-contained components. then draw up a high level spec detailing the components and code required

so far i have the following classes

ADOFunctions - close/dispose datasets, connections etc
ConversionFunctions - StringToNull, DateToNull etc
DataClass - Dataset stuff like fill, move next, get/set current row etc
EncryptionFunctions - self explanantory!

ErrorHandling - what all should be in it - bit perplexed by this one. usually we just display the error message as a msgbox - but should i be handing different exceptions in different ways?

MailFunctions - sending emails etc
OracleADOFunctions - adding parameters, creating commands etc
SQLADOFunctions - same as above except for SQL
ValidationFunctions - validating textboxes, combo's etc
WebFunctions - little serverside javascript injections for disabling buttons, display messageboxes etc
WindowsFunctions - havent got any as yet!

Controls
WebForms Controls
WinForms Controls

WebForms UserControls
WinForms UserControls

EnumsClass - generic enums used by all projects

anything there ive missed, or should be including??

Cheers,
Craig