Making fonts larger in apps under Lion
Google Chrome

Its own UI, not web pages

The following settings in TinkerTool affect the following pieces of Chrome's own UI:


Chrome address bar, i.e. URL:  System in TinkerTool (default font: Lucida Grande; largest size possible is 16 pt; larger sizes are truncated)
titles of tabs:  Help tags (default font: Lucida Grande; largest size possible is 13 pt; larger sizes are truncated. Bold is ignored, it's always Regular)
Chrome's ex-Wrench menu (top right corner): Messages (default font: Lucida Grande; upper limit is something like 24 pt, further increasing the number has no effect)


Web page content


Default zoom: Wrench > Settings (⌘ ,) > Show advanced settings > Web content > {Font size, Page zoom}. Both also affect how Settings page is zoomed. 
For a particular site: ⌘ + / ⌘ -