The lead's activity log records all details of form fill out. The entries are labelled "Fill Out Form".
A short example highlights the contents:
Activity Details – ID 613687
Webform ID: 1074
Form Fields:
FirstName: B
LastName: Gomes
Email: test@marketo.com
MainPhone: 000-000-0000
PostalCode: 000000
_marketo_comments:
Webpage ID: 1879
Query Parameters:
Referrer URL: http://marketo.themeat.org/bgomes_basic_lp_2.html
Client IP Address: 213.94.0.0
User Agent:
Mozilla/5.0 (X11; Linux i686) AppleWebKit/534.34 (KHTML, like Gecko) rekonq Safari/534.34
Lead ID: 64705
The "User Agent" is the browser used. Most will start with Mozilla/5.0, an inheritance from the browser wars from early 2000's. The last part is the actual browser ID and compatibility with similar browsers.