Secondary structure of tRNA (left is wild-type tRNA-Trp; right is suppressor mutation that can rescue a mutation in a Trp codon)
(from: http://www.life.uiuc.edu/micro/316/topics/rev-sup/sup-tRNA.html)

Secondary structure of a small ribosomal subunit (16S) rRNA.

This example is from a hydrothermal vent organism that grows at 65 C; Eubacterium thermomarinus)
(from: http://www.mbio.ncsu.edu/JWB/MB409/lecture/lecture07/lecture07.html)

Below, is a diagram of the secondary structure of a large ribosomal subunit (23S) rRNA. This example is from a photosynthetic bacterium called Synechococcus. Because of the large size of the large ribosomal subunit rRNA, the molecule below is shown in two halves (5' half, and 3' half)
(From: http://www.mun.ca/biochem/courses/3107/Lectures/Topics/Ingredients.html)

5' half:

3' Half: