Question: The font size I need to match the design I have is 85pt, which is extremely large. In IE6 and IE7, my design is affected because the divs that contain these elements become larger than they normally are, and as a result, elements under these are pushed further down, somewhat breaking the design. I have the height defined for these elements and when I decrease the font size, the elements begin to shrink to the correct size. I've added line-height: 0; to the element and this works in all modern browsers.

Unfortunately, the design I'm working on cannot be shown publicly, but I was hoping to get some insight into other possible techniques that I could try to get the design to render correctly. The height of the parent element is 144px, which includes 10px padding on top and bottom and a top and bottom 1px border.

Unfortunately there's not a lot more that I can add to this, but I'll include whatever info I can if asked.

Answer: 
Thank you all for your input. Originally I needed absolute positioning on the element in question, while the parent element had relative positioning. However, using this with line-height: 0 caused the text to disappear in IE6 and 7; after trying to figure out where the text was initially, I removed absolute positioning and decided to leave the text left aligned in IE6 and 7, which affected the position of other elements as a result. I revisited the original absolute positioning and added border to the element to reveal its location. Doing this showed that it was exactly as I defined it: an element with a line-height of 0px, so the top and bottom borders were next to each other. For IE6 and 7, I defined line-height: 100%; and my text was almost where I needed it. I added top and the needed pixels and now my element is in the correct position with its line-height not affecting any of the other elements because of the positioning.

Thank you all again for your assistance.
My first thought when reading your post was to adjust the line-height, but since you've already done that, I'm not sure how much more can be done. From your summary, I gather that the design cannot be modified to account for the large font sizes.

Another answerer recommended using pixel sizes, but I would recommend using ems as they are percentage dimensions and will be more consistent across browsers, screens, and resolutions.

Line-height can be left as 0 (or set it to the height of the parent element), but you will likely see the text floating over other elements if the text's height surpasses the line-height.

Any possible way you could use an image for the text instead? That's really the only fool-proof method for getting all browsers to look consistent.