Consider using the Matrix field_type by Pixel & Tonic, see Pixel & Tonic: Matrix This will allow you, the applicant to enter as many rows of like formatted data as needed.
You would define the areas, similar to a table. So the subfields could be: from (mm/yyyy), to (mm/yyyy), position, company, summary, reason for leaving.
The info could be laid out how you like, say something like:
**From To Position/Company**
**Summary/Reason for Leaving**
05/2012 09/2012 Web Developer, Prince and Stadtler
Summary: Worked developing photo exhibit section for project specific to user feedback stories.
Reason for Leaving: Contract Ended
...
01/2012 04/2012 Database Developer, Synchronized Beings
Summary: Switched company from MySQL to MongoDB.
Reason for Leaving: Contract Ended
The form would place a single instance of the fields to be completed. The applicant, would then select to add more rows, as needed, similar to adding jobs or projects to LinkedIn.
Matrix works well for these types of situations, where there would be an unknown amount of, but similarly formatted responses. It could also be used for a skills field, etc.