AFAIK you cannot create a sharing rule at runtime. But yes you can share the opportunity to the user (which as per you question is a field in the oppty). You can insert a record in the opportunityShare object which will give either read or write access. You can add the below code in the an after insert trigger / after update trigger of opportunity.

opportunityShare opptyShare = new opportunityShare();
opptyShare.OpportunityAccessLevel = 'Read';// other values that can be added are 'Edit' and 'All'
opptyShare.OpportunityId = opptyID; //add the oppty Id which you want to share.
opptyShare.UserOrGroupId = userId; //add the UserId which to which you want to share the oppty
insert opptyShare; // insert the oppty share records.


You can read more about it here : http://www.salesforce.com/us/developer/docs/api/Content/sforce_api_objects_opportunityshare.htm

Creating Sharing Rules on run-time(While opportunity is being saved/edit) using apex code
I'm working on a ERP / Accounting (lots of tables and data) web app and was wondering what color scheme would be appropriate for this type of application? Users will be sitting in front of their computers for 8+ hours enetering lots of data on daily basis and I would like to  make that experience as comfortable as possible to their eyes.

Most of these application I've seen are using some sort of a white/grey/blue scheme with white being dominant but I'm concerned that this color might strain their eyes to much especially considering different brightness of monitors and working in the dark. 

Any help would be appreciated.
