System privileges commonly granted to users

What privileges should you give your users?
The generally accepted answer to that question is: "as few as possible," while still enabling them to do their work.
To end-users, who only connect when running an application, I generally give the

CREATE SESSION

privilege, whatever object privileges and roles are required by the application, and nothing more. That allows them to log in and use their application, and that's all you want them to be able to do.
Developers often require the ability to create objects. I usually end up granting them the following privileges:

1. CREATE SESSION
2. CREATE TABLE
3. CREATE DATABASE LINK
4. CREATE SEQUENCE
5. CREATE PROCEDURE
6. CREATE TRIGGER
7. CREATE VIEW
8. CREATE SYNONYM
9. ALTER SESSION

These privileges allow developers to connect, and to create objects such as tables, views, and so forth. Developers often need these capabilities in order to test code or to experiment. Note however, that this applies only to those databases used for development.
It is very rare for me to grant the ANY privileges, or the specific system-wide object privileges such as CREATE TABLESPACE.
These represent tasks that are best left to the DBAs.