You could create a simple list of time slot objects (e.g., every 30 minutes) and let users pick from a dropdown.
These objects can be created as non-persistable objects when you load the page.
If you need a more interactive control, you can build or extend a pluggable widget to handle fixed increments.
Hi Gal,
You can make enumeration for 30 mins difference like 10AM-10:30AM, 10:30AM-11:00AM according to your need & use dropdown value where select this enumeration as attribute.
Hope you like the ans