You know what I'm talking about...sharing a username/password among various members on the team, allowing multiple individuals to log in with the same username and password.

I'm not even going to get into the legalities associated with having shared licenses. 

Here are some of the problems you open up by sharing licenses:

• You're unable to use Chatter. Chatter lets you @ mention people, to tag them, ask someone a question, remind a colleague to take action. If you use a shared license, when anyone @ mentions that user, G-d only knows which person is actually going to get that notification. And, I'm sure you've heard of Murphy's Law. ....The person who gets that email won't bother opening it up to look at it. Let alone, even if they do, when you respond...the person on the other side doesn't know the identity of which person actually replied. Let me ask you - do you also share email accounts, and phone numbers, sending and receiving emails, phone calls and text messages with other people? Yeah...that's a bit nuts.
• You're unable to see who was the last person that modified or created anything in Salesforce. Out of the box, on practically every record you have 2 system generated fields: "Created by" and "Last Modified by" ...if you're sharing licenses with other people, your guess is as good as mine to try and figure out who, among the various people sharing a login was the actual person who created or last modified that record.
• You're unable to assign tasks. How do you assign tasks to a shared user, when anyone else logging in to that account sees all the same tasks assigned to them?
• Your metrics are useless - all opportunities, accounts, contacts assigned to a shared user become meaningless, because no one knows who is truly working on those records.
• You're unable to access any filters for "My Contacts, My Accounts, My Opportunities, My Activities."

In a nutshell - you're setting yourself up for lots of unnecessary confusion.

How do you solve it? 

Simple.

Each person should get their own unique username and password.