The article has good ideas but I have to agree that re-installing on a Mac is a very rare event and relatively time consuming (to the other options).
Now my 2 cents:
1) Use OnyX a well tried, free and frequently updated utility that will clean cache files, run some UNIX maintenance scripts and even has some Finder default options. It is available at http://www.titanium.free.fr/ and pretty much everything you might need in that area.
2) Upgrade your hard drive. If you have a MacBook you absolutely have to try Seagate Momentus XT Hybrid hard disk. It's a combination 7200 RPM disk with built-in flash memory that will knock your socks off. Just make sure it has the latest SD25 firmware installed as some issues were reported with the original firmware. We have installed a dozen of these at our office's laptops 8 PCs and 4 Macs with not a single issue. Overall performance gains are very good but on booting and on virtual machines is simple astounding. 500 GB will cost you USD 99.
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