There is a whole industry of Act! developers that write tools to extend Act!’s functionality.  Some of them publish free tools so you can “Get to Know Them” before purchasing other services from them. Each plug in works on certain versions of Act!. Check their page and your version of Act! before downloading.   This website offers several free tools as well.

Function
Left Alignment Fix for Act! 2011 Download
Change Default Lookup Field Download
Reschedule Multiple Activities at Once Download
Layout Designer Tool Download
UniqueID Generator Download
Lookup Bad E-Mails Download
History Window Fix Download
Durkin Tools
E-Mail Address Lookup Tool