SQL Server: how to avoid sysadmin rights but give adequate rights
For server logins, you can grant "securityadmin". The "newer" way is to run 

GRANT ALTER ANY LOGIN TO AColleague


Edit: Securityadmin allows someone to bootstrap themselves to sysadmin. Not good. Don't know how to workaround this at the server level

For jobs, look at the "SQL Server Agent Fixed Database Roles"

For maintenance plans, it looks like "sysadmin" only