What are the products from nuclear fission?

I'll list some of the more important products from nuclear fission and put them into three categories.

The Good:

Neutrons - they have a short half-life so they don't contaminate the environment, and they allow sustainable fission in reactors to happen.
Photons - they (x-rays, gamma rays, etc.) provide the energy that is converted and then distributed by nuclear reactors.
¹³⁷Cs - it is one of the most used gamma-radiation energy sources for the calibration of medical and scientific instruments.

 

The Bad:

¹³⁷Cs - I'll put it here too since it's pretty long-lived (t_1/2 = 30yrs.), and can contaminate the environment.
⁹⁰Sr - it easily contaminates calcium-deficient plants and has a half-life of 29yrs.
¹³⁷Xe and ⁹⁰Kr - these two are noble gases and so can easily diffuse throughout the atmosphere, decaying into longer-lived isotopes which can then contaminate.

 

The Ugly:

¹²⁹I, ¹³¹I, and ¹³²I - these guys get collected and stored in the thyroid gland and are also 100% absorbed into the human gastrointestinal tract.
³H, a.k.a., tritium - an aqueous solution of tritium can easily be absorbed through the skin.
⁹⁹T - a VERY long lived beta emitter. It can chemically form into many hazardous and soluble compounds, and with a half-life of 211,000 years, it's not going away anytime soon.