Installation, Administration and Maintenance of SQL Server Instances. (Installing SQL Server)
Setup Test, Dev, Staging and Production Environments. (Installing SQL Server)
Create Users and assign permissions based on the level of database access the user would need. (Security)
Create Linked Servers to SQL Servers and other databases such as Oracle, Access, Informix etc. (Security and General Administration)
Design database Backup and Restoration Strategy. (Database Backups and SQL Server Agent)
Once created the database Backups, monitor those backups are being performed regularly. (SQL Server Agent)
From time to time recover the databases to a specific point of time, as per the requests. (Database Backups and Recovery)
Setup High-Availability as part Disaster Recovery Strategy for the Databases. (Failover Clustering, Database Mirroring, Log Shipping and Replication)
Troubleshoot various problems that arise in a day-to-day work and fix the issues. (Monitoring SQL Server Error Logs and checking your email alert (if there is one configured))
Monitoring and Performance Tuning; Physical Server Level, Database level (Database settings and options) and query tuning. (Creating and maintaining those Indexes, not performing database shrinking, memory settings, monitoring CPU usage and Disk I/O activity etc)
Documenting major changes to the SQL Servers. (General)
Apply Service Packs. (General)