Recommendations for appending address data to leads

Hello all - wondering if anybody's got recommendations for a solution for adding address data to leads. For example, given a company name, being able to add full address data to the record. This would be very helpful in our lead assignment process, without increasing the # of required fields in a form. I've seen this type of thing integrated into forms on web sites, and I know there are options for adding that kind of data separately from the initial form completion - would lvoe to hear others' experience with this.