Yep, great idea. Just add some simple formatting rules and require that the email is sent from a registered email address, and include a password field to prevent fraudulent adding...

Example Email:

ACCOUNT[1299439]
PASSWORD[Pas$w0rd;12345]
FIRST_NAME[Bob]
LAST_NAME[Smith]
EMAIL[bob@exmample.com]
PHONE[123-456-7890]
MOBILE[012-345-6789]
COMPANY[Example Company] (Create this if it doesn't exist)

etc...

This would likely be an easy change... if you use PHP/MySQL it would be from "WHERE field_name LIKE '{$search_words}%'" to "WHERE field_name LIKE '%{$search_words}%' (just add a '%' before the search term). Good suggestion.