Here is the link for the location of ACS Summary File Technical Documentations.
In this example is the tech doc for the latest 5-year summary file release. Appendix F (p. 80, pdf 82) contains the different summary levels available in the data release. Appendix E (p. 44, pdf 46) is what you are looking for which details the name of each table, whether it is available at the block group level and the location of the data.
StackExchange won't let me post anymore links unfortunately. So the rest won't appear as links.
Below is the location of the of documentation for the 2010 Decennial Census Summary File 1:
The information is compiled in the technical documentation below:
The information you are looking for is in Chapter 4 (p. 4-1, pdf 107) and Chapter 6 (p. 6-21, pdf 183). Chapter 4 contains all of the geographic level data is provided for (might be too much information). Chapter 6 contains the list of all tables available in the data release.
They are divided into type main types, tables starting with P (generally information about population) and H (information about houses).
By default, the tables will have information down to the Census Block level, but if there is a 'CT' attached to the table name, then the information goes down to the Census Tract level, and if there is a 'CO' attached to the table name then the information goes down to the county level.