You can hit the error "Maximum request length exceeded" if you are attempting to upload large files with ASP.NET
The web.config setting below changes the max size to 100MB
<httpRuntime requestValidationMode="2.0" executionTimeout="240" maxRequestLength="102400"/>
If you have used ASP.NET to upload documents into a database and got the error "There was an error opening this document. The file is damaged and could not be opened."
If you are using a DataSet and TableAdapter check the parameter on the stored procedure (if you used a stored proc) the size probably defaulted to 65336. Change it to -1 and you will be all set.

After (type is -1 and tab to the next field)

Check out this ASP.NET example over at Dev Fusion. Very simple, very elegant.
Sample download included here for reference.
treeviewv2article.zip (152.45 kb)