99% of the scripts we use are in house or customized from sites like SQLServerCentral.com

That being said, there are a couple third party tools that are worth their weight in gold such as ones that compare databases on a QA/Development Server with their eventual incarnations in production. Any script involving heavily used remote logins, I'd always be hesitant about.

That being said, there's a cool feature about SQL 2008 Management Studio I read about at http://www.sqlskills.com/BLOGS/KIMBERLY/post/SQL-Server-2008-Central-Management-Servers-have-you-seen-these.aspx where for example, you can right click on a group folder, such as where you have a group of QA Servers bundled up, and query that entire group. For example, right click on the folder, select new query, and a query window opens up. Any query done in that window is run against the entire set of servers in that grouping. This type of integration could provide DBA's more power to create even more powerful customized scripts.