One thing I currently do on the ASP Techniques (asptechniques.com) web site is store all the content in a SQL Server database. Because I have some long text articles, I store these in ntext fields. The problem is that in SQL Server, ntext fields are not searchable using the LIKE keyword. This makes performing keyword searches basically impossible.
However, using the Full-Text Indexing feature of SQL Server, I can support keyword searches. You specify the table(s) and field(s) to index and SQL Server automatically creates a full-text index of those fields. The best part is that the SQL query still uses the same LIKE keyword. It’s basically transparent at the SQL level and since the indexing runs automatically when the system isn’t busy, it doesn’t put extra work on the server while you’re using it.