Recently I have been trying out quite a few scripts and plugins to speed up my work flow in 3ds Max. I highly recommend browsing scriptspot.com for useful scripts. But to save so time and kick you off here is what I have been using recently. Please note that not all of these are available on Sciptspot but there is a link to each download. So in no particular order here are my Top Five Free 3ds Max Scripts and Plugins. Wireframe Render jokermartini.com/2010/04/30/wireframe-render/ Wireframe Render is a script from John Martini over at jokermartini.com. I have found this one very useful for creating wireframe renders for Turbosquid for example. Wireframe Render uses a simple interface that enables the user to quickly and easily create wireframe renders. I would also recommend checking out some of John's other cool tools available at jokermartini.com/extras/ including cobwebs and Select Intersectors.
https://vimeo.com/26107414 Center and Reset www.scriptspot.com/3ds-max/scripts/frodos-magic-scripts-pack This neat script is from Frodo's Magic Scripts Pack. It resets the xform on an object and centers the pivot point in one click. I use this alot and find it to be a big time saver.
Ivy Generator hass been around for a while now and I think it is great. I am always looking out for places I can put it in my scenes because it looks great and it is so easy to use. It is also very customisable with your own leaves etc. Here is a great video tutourial from Sachin Joshi over at CGTuts.