Is it possible in Google Spreadsheets to reach the value of the cell just above?
Meaning: In one cell A2 I want to display the value from the cell above
You can address it like this:
=INDIRECT(ADDRESS(ROW()-1,COLUMN()))
COLUMN() returns a numeric reference to the current column
ROW() returns a numeric reference to the current row.
In the example here, subtracting 1 from the row gives you the previous row. This math can be applied to the ROW() and/or the COLUMN(), but in answering your question, this formula will reference the cell above.
Then we have ADDRESS() which accepts a numeric row and column reference and returns a cell reference as a string.
Finally INDIRECT() allows you to pass a cell reference in as a string, and it processes it as a formula.
Google Spreadsheets give you help hints as you type, so you should get a full explanation of each function as you type the formula above in.