Code Library High-Performance VBA String Concatenation with clsStringBuilder clsStringBuilder takes a collection-based approach to speed up string concatenation.
Code Library clsConcat: Blazing-Fast String Building Performance in VBA You don't need to understand how to pre-allocate a memory buffer in VBA to take advantage of this blazing-fast string builder class.
Class Modules Better Global Constants in VBA with Dot-Driven Development My global constant "C" class--with PredeclaredId = True--is a great alternative to traditionally-declared global Public Const's.
Class Modules Great Intro to Class Programming in VBA Former Access MVP Ben Clothier's primer on class programming in VBA should be required reading for all Access developers.
Class Modules Caching Object Instances in VBA Classes Simplify the object initialization code in your class modules without sacrificing performance using this easy technique.