Hi Manisha,
A Punch Line or Caption is a VERY powerful tool to have and so great thought must go into it, because if you get it wrong it will do more damage to the company image than good.
Consider these examples:
1. Microsoft - Where Do You Want to Go Today; Your Potential Our Passion
2. Windows XP - Do More with Less
3. HP - Invent; everything is Possible
4. Computer Associates - The software that powers the E Business
5. CSC - Experience. Results.
6. Accenture - High Performance. Delivered
7. IBM - ON DEMAND
8. LENOVO - We are building a new technology company.
9. Apple Macintosh - Think Different.
10. TCS - Beyond the Obvious
11. Infosys - Powered by Intellect, Driven by Values;Improve your odds with Infosys Predictability
12. WIPRO - Applying Thought
13. EMC - Where Information Lives.
14. Adobe - Simplicity at work. Better by adobe.
15. Macromedia - What the web can be
You will note that every one gives a message and that is what you need to do. Your message can be about your product; your service; your vision; your values; your foresight and so on.
You must also decide as to whom the punch line/caption is intended for, Clients, Candidates or both.
We found it very useful to involve ALL the staff and ask for their inputs, in fact we turned this into a competition..... the Prize? the winners name and photograph on the website !!
This also acts as an indirect motivator.
Hope the above helps,
Regards,
Harsh