How to update Lead fields with Account data?

I don't think there is a good way to do this within Marketo. Possibly there are solutions in SFDC, but I'm not aware of one.

Out of curiosity, what object do your sales reps work from? If we had leads that we knew aligned to one account, they'd be converted so that reps could see everyone at that account in one place.

Our Sales reps use Accounts and Contacts, but our Telemarketing reps use Leads.  Sales management has asked that we not automatically convert Leads to Contacts unless Telemarketing has vetted them first to prevent unqualified people cluttering the Contact list at the Account.  Once Telemarketing qualifies a Lead as ready for a Sales rep, they convert it to a Contact / Account / Opportunity as appropriate. 

We do have a lookup relation between Leads and Accounts and a Lead related list at the bottom of the Account record, but don't have an automatic way to update the Account field on the Lead record if the Lead's email domain is the same as the Accounts email domain.  I investigated creating a cross-object workflow in Salesforce to do this, but it will only work if there is a master-detail relationship.  This may require using APIs to accomplish. 

It would be great though if Marketo provided a lookup table capability.  For example, I have smart campaigns that normalize Country and State field values to the 2 character ISO standard (in case they get past field validations in forms and SFDC), but the Change Data Value flow step has 50+ choices - not the most efficient way to do this.