More things you can't do on amateur radio
First of all, amateurs are forbidden from broadcasting: that is, amateurs are prohibited from making transmissions of content transmitted with the intention that it be heard by the general public, either directly or indirectly. That doesn't mean that hams aren't allowed to make one-way transmissions, it just means that an amateur may not use his or her amateur station, in general, to talk to people who aren't also amateurs. It's important to understand that certain one-way transmissions such as a CQ call, QST bulletin, or telemetry transmission are not "broadcasts" because they are not intended to be heard by the general public, but instead by "all amateurs" or "amateurs with an interest in this communication". The key to the definition of "broadcasting", which is entirely prohibited to the amateur service, is that the communications must be intended to be received by the general public. Obviously this regulation is to prevent amateur stations (with their zero license fee) from competing with the broadcast service. If your interest in radio is to be a talk radio star, then amateur radio might not be you, and you should consider looking elsewhere.
Similarly, the transmission of music is also prohibited (with one exception: music incidental to an authorized retransmission of communications from the Space Shuttle is permitted). However, there is reportedly a ruling that one ham singing "Happy Birthday" on the air to another ham does not count as the "transmission of music", presumably because most hams seem to be unable to sing. Again, this is a noncompete regulation; if you want to transmit music the FCC wants you to use the broadcast service or a low power service to accomplish your purpose, not amateur radio. If your interest in radio is to be an on-air DJ, again, amateur radio might not be for you, and you should consider looking elsewhere.
The use of codes, ciphers, encryption, or any other method for concealing meaning is prohibited, with two exceptions that are very similar in nature. A station may use encrypted transmissions for the telecommand of an amateur space station (that is, an amateur station more than 50 kilometers above the earth's service; typically, a satellite, either manned or unmanned), or for the remote control of a model craft (such as a model airplane, boat, or car). In the satellite station case, the FCC mandates that all satellite stations be able to be "remote killed" from the ground, and in any case a malicious operator could easily pervert a satellite's operation by tweaking its control parameters to the point that it could not be recovered. Given the high expense of putting satellites in orbit, and the extreme difficulty in servicing them once they're there, the FCC lets us protect those stations in this way. The same permission is granted for remote control craft for much the same reason; also, telecommand stations for remote control of model craft are subject to power limitations (one watt) that make it unlikely that the remote control transmissions will create difficulties for other stations, and to physical identification requirements that will allow identification of the station operator in the unlikely event that there is unacceptable interference.
Amateurs may not send "false or deceptive signals". This mainly means that amateurs may not use fictitious identification to try to appear to be someone they are not, or to try to get someone else in trouble. It also means that, e.g., false calls of distress are bad (but we've already covered that).
Amateurs may not use indecent or obscene language on the air. This one is probably one of the most violated rules on the bands, sad to say: there's quite a lot of indecent and no small quantity of obscene language on the HF bands (75 meters is especially notorious for this) as well as on VHF and UHF repeaters in many areas. What exactly is meant by "indecent" and "obscene" is complicated, and it's probably best to play on the safe side here, not so much for the sake of not violating the rules, but simply out of respect for not only your fellow amateurs (who may well be very much not like you) but also anyone else who might be listening in. Remember that kids, and even entire classrooms, listen to this stuff sometimes, and your name and address are published by the FCC so (unless you've been making "false or deceptive signals") anyone who does hear you swearing on the air will be able to find out exactly where you live. And that might prove to be embarrassing.
This post has been brought to you by pool questions T2A01, T2A02, T2A03, T2A04, T2A06, T2A07, and T2A08.