Upgrade your unibody MacBook Pro to 8GB
One bright spot in the otherwise rising memory prices (eg Mac Pro) is that you can now get 8GB for your MacBook Pro unibody at OWC for under $500. Apple charges $1000 for 8GB, so that’s a huge savings. OWC will also take your existing 4GB for $45 cash-back (4GB eg 2GB modules are worth little because they use readily-available lower density chips).
Don’t have a MacBook Pro? Get a refurbished one and save 15%.
Installing 8GB is the best way to increase performance with memory hungry apps like Photoshop CS4, Lightroom, etc. Especially with Snow Leopard (see review), memory is more useful than ever.
I use OWC modules in my Mac Pro (review) and MacBook Pro (review), and they work flawlessly.