Opportunity Teams
Avoid duplicate opportunity records created by each member of a sales team. Instead, create an Opportunity Team so that all the members of a team can access the same record. Enabling Opportunity Splits also lets you use opportunity splitting to share credit among team members
https://help.salesforce.com/HTViewHelpDoc?id=salesteam_def.htm&language=en_US (https://help.salesforce.com/HTViewHelpDoc?id=salesteam_def.htm&language=en_US)

Opportunity Teams aren’t the same as Account Teams, although they share the same set of available team member roles. Opportunity Teams work together on opportunities, while Account Teams work together on accounts
https://help.salesforce.com/apex/HTViewHelpDoc?id=customize_teamselling.htm

Setting Your Default Opportunity Team
An opportunity team is a group of users that typically work together on opportunities. For example, the opportunity team may include the account manager, the sales engineer, and the sales representative. Your default opportunity team should include the users that you normally work with on the opportunities that you own. You can specify the role that each user plays on your team and the specific access that each user should have to your opportunities
https://help.salesforce.com/apex/HTViewHelpDoc?id=user_salesteam.htm&language=en (https://help.salesforce.com/apex/HTViewHelpDoc?id=user_salesteam.htm&language=en)

Add Members to an Opportunity Team
1) Open the opportunity and navigate to the Opportunity Team related list, then click Add.
2) Enter the member’s name in the User column. If the partner portal is enabled, choose whether the member is a Partner User or User, and then enter the member’s name.
3) When you add an opportunity team member, the member is automatically granted read access to the associated account.
4) Select the member’s opportunity team role.
5) Select the member’s opportunity access level. The access level can’t be less than your organization’s default opportunity sharing access.
6) Specify values for any custom fields that your administrator has created for opportunity teams.
7) Click Save.

Run the Opportunities with Opportunity Teams report to list the opportunity team members for the opportunities owned by you or users below you in the role hierarchy. The report also shows information about opportunities you own and opportunity teams to which you belong, including any opportunity splits.

http://certifiedondemand.com/overview-of-account-teams-opportunity-teams-in-salesforce/

Please let me know if this will help  you

Thanks,
Amit Chaudhary