Consider:

Clustering - Provide failover to another server should the active server running the database fail (not including SAN). This is not a full DR solution (unless you have a mirrored SAN offsite with associated 2nd cluster).

http://www.sql-server-performance.com/2002/clustering-intro/

Log shipping - Can be onsite, offsite and the latency is fully configurable and dependent on bandwidth

http://www.sql-server-performance.com/2002/log-shipping-70/

Mirroring - similar benefits to log shipping but much easier to configure. Requires SQL 2005 and later.

http://technet.microsoft.com/en-us/library/cc917680.aspx

...also consider replication..

Robert Murphy