I try to produce fairly consistent negatives, so that I'm usually within grade 2 or 3, and if there's something that really doesn't fit that I have to print, then I can use VC paper.

That aside, there are methods like water bath development and two-solution development that can be used to get in between grades. Ansel Adams, for instance, controlled contrast by using both Dektol and Selectol Soft, and increasing the proportion of Dektol time for more contrast or the Selectol time for less contrast.

Another good technique that I use occasionally is intensifying negatives with selenium toner. This can often give you a one zone expansion for a flat neg.

If you just want to get more sparkle in the highlights, local bleaching is an option with potassium ferricyanide. Yet another method to increase overall contrast is to print a bit dark and then bleach the whole print, which Les McLean has mentioned here and in his recent book.