1. The Enterprise runs into a mysterious energy field of a type it has encountered several times before.
2. The Enterprise goes to visit a remote outpost of scientists, who are all perfectly all right.
3. Some of the crew visit the holodeck, and it works properly.
4. The crew of the Enterprise discover a totally new lifeform, which later turns out to be a rather well-known old lifeform wearing a funny hat.
5. The crew of the Enterprise are struck by a mysterious plague, for which the only cure can be found in the well-stocked Enterprise sick-bay.
6.The Captain has to make a difficult decision about a less advanced people which is made a great deal easier by the Starfleet Prime Directive.
7. The Enterprise successfully ferries an alien VIP from one place to another without serious incident.
8. An enigmatic being composed of pure energy attempts to interface to the Enterprise's computer, only to find out that it has forgotten to bring the right leads.
9. A power surge on the Bridge is rapidly and correctly diagnosed as a faulty capacitor by the highly-trained and competent engineering staff.
10. The Enterprise is captured by a vastly superior alien intelligence which does not put them on trial.
11. The Enterprise is captured by a vastly inferior alien intelligence which they easily pacify by offering it some sweeties.
12. The Enterprise visits an earth-type planet called "Paradise" where everyone is happy all of the time. However, everything is soon revealed to be exactly what it seems.
13. A major Starfleet emergency breaks out near the Enterprise, but fortunately some other ships in the area are able to deal with it to everyone's satisfaction.
14. The Enterprise is involved in a bizarre time-warp experience which is in some way unconnected with the Late 20th Century.
15. Kirk (or Riker) falls in love with a woman on a planet he visits, and isn't tragically separated from her at the end of the episode.
16. Counsellor Troi states something other than the blindingly obvious.
17. The warp engines start playing up a bit, but seem to sort themselves out after a while without any intervention from boy genius Wesley Crusher.
18. Wesley Crusher gets beaten up by his classmates for being a smarmy git, and consequently has a go at making some friends of his own age for a change.
19. Spock (or Data) is fired from his high-ranking position for not being able to understand the most basic nuances of about one in three sentences that anyone says to him.
20. Most things that are new or in some way unexpected.