In SQL Server 2008 R2 I made a single row table that had Application Settings.
In order to enforce a table constraint of one row, create the table with a PK constraint on and id column with a CHECK contraint of idCol = 1. This will do two things, it will enforce that every row is unique and not null with the PK and the CHECK will ensure that the only val possible is 1.
Then, all you have to do is insert a row with id 1 and all other columns are setting vals (global settings for the app). If you need multiple settings, join tables to this one.
For Multi-tenant applications, consider adding a table for tennant specific settings. This table is for global settings only.