Here are some tips:
1. Config.trim_on_minimize set to true. This allows Windows to reclaim memory when the program is minimized (a feature prominent in IE 7). This value may not be on by default in Firefox. You may need to go to about:config, right click to add new boolean, and set it to true.
2. Browser.sessionhistory.max_total_viewers set set to '0', i.e. 32 MB.
With these optimizations, and disabling of unnecessary extensions (like 'DOM Inspector'), I managed to run Firefox under 45 MB with 5 Ajax-based websites opened in tabs. More tips on reducing memory usage here.
Recently, Yahoo launched an electronic Time Capsule. This was overshadowed by a bigger news - Google acquiring YouTube for 1.6 billion bucks. [This was close to the initial estimates and rumours that were flying all over the blogopshere before the deal was sealed.]
Its a classic Silicon Valley story. And indeed, those are very, very happy men.
In addition, Microsoft just set a new record by releasing patches for fixing 26 security holes. Wow! =p