I rarely recommend software, but this has proved of value to me in my prospecting and contact phone calls so search the web for a copy of "ThroughClock", and install it if you want to experience what I feel.
The display can be customized, to an almost-transparent clock, positioned anywhere, and all the usual stuff.
Here's how it really helps me:
I dial a follow-up or a contact call and get their voice-mail.
I don't want to leave a voice-mail on this issue, so I tell ThroughClock to pop up a reminder every hour, and paste in as the message the contact name and phone number (with extension).
On the hour, the pop-up tells me in effect "Try again; they may be in!".
In a Meeting
Sometimes the person picks up the phone to say that they are in a meeting, call back tomorrow. Sure, What's a good time? Two o'clock.
ThroughClock is set for two-o'clock Friday, again with the name and number.
If, like me, you have a contact list that displays names to be called ("follow-up") today, you can set one event on ThroughClock with the message "Follow-ups", which will remind you throughout the day to try all outstanding numbers again in an attempt to reach people between-meetings or between lunch breaks.
Cool Tool for prospectors.