Max, Maxene, and Marvin go into a bar...
Coming up with good names for a story can be quite challenging and an enormous pain in the ass.
If Will Farrell's character is named Bobby and Harrison Ford's character is named Berry you are not going to mix those two up on the screen. On the page it's another story. If your character names are too similar they can bleed into one another and make it confusing for the reader. I also stay away from ambiguous names or using girls names for boys and vice versa.
I like strong names for my Hero's but seriously, not everyone can be named Jack. I tend to use names of my friends for the good folks and names of people I can't stand for the assholes in my script. A neat side effect of doing this is that it helps me keeps my characters straight.
I also make an effort to not have any character's name start with the same letter. It's stretching it a bit but it makes me be creative with names.
When I snowplow and I find myself getting hung up on names I default to Hero, BadGuy, Girlfriend, Henchman, Hotshot, etc. This way I can continue getting the good stuff down on the page without staring at the screen. Find and replace is your friend.
-Jim