It's doable, but "8 totally separate databases" seems a bit unusual. Usually there is some sort of link between your data or there'd be little reason to pull them all up on the same screen at the same time.
Relate you 8 tables of data with the X operator instead of = to a 9th table. This operator matches them with a "match all values" logic so that you can match any record in the master table to all records in each of the other 8. That gives you these relationships:
Master::anyfield X Table1::Anyfield
Master::anyfield X Table2::Anyfield
Master::anyfield X Table3::Anyfield
and so forth...
Then you can put your tab control on your Master layout and put portals to each of the 8 tables on eight different tabs.
There is another way too which will allow you to filter the records that show in each tab. (Phil's 9th table)
You can create a table called Global Display keys where all the fields are set to Global Storage.
You would have 8 (or more fields)
the fields would be something like tablename1_keyfield, tablename2_keyfield etc.
You would create a relationship between each of these tables key field and the appropriate field in the Global Display Key table (GDK)
You would then create a layout with the GDK table as the main table.
Then you can add GDK fields and drop down boxes, radio buttons etc. (changing the values in these fields will show the appropriate records from the related table)
add your tab control then you would put portals on each tab such as Phil suggests for each table.
You can even script the population of all the keys in the GDK table based on entry of one of the other fields
The only issue with this is that you must have 1 record in your GDK table in order for the portals to display.
You can control this with a simple startup script to Go to a layout that is just the GDK table delete all records and then new record request.
I agree with Phil that this seems a bit unusuall as there are probably links between the tables that might not be enforced right now but should be explored. (ie key values are not equal but are consistent as in the Make of car in one table may be Honda but an accessories table may have the values be HND)
Great. Thanks. I'll figure out how to do this and post back later.
You can combine this technique with another Main table by either
1 adding another id field to the GDK for that table and linking it to the GDK table by that Key (this is what I do and add an OnRecordLoad script trigger to set and clear GDK fields.)
2 using phils X relationship beteen the GDK table and the Main table.