Can you please tell us why you want to store 50 - 100 million variable length strings into an array in the first place? Is it for sorting purpose? Or is it because you want to find a particular element from the array? There are lots of algorithms to choose from depending on the problem dealing with. Perhaps you should give a bit of overview on the type of problem you are trying to solve.
In general, you could however store your strings in a file or database as suggested by davido and Zaxo, depending on your application of cause.
Personally I would favour the direct file approach, database insertion is a relatively expensive operation. Unless of cause if you use commands like 'bcp' in Sybase (just an example) that does native database import that is very fast.