Great stuff! I've been keeping book notes in a personal wiki for years, and I can attest that it helped me better remember what I learned, and having something to refer back to has been invaluable.
More recently (Last 4-5 years), I've started dumping hard-to-remember bits of code/commands/configs into a snippet manager like TextExpander or Alfred. (I'm told Dash is also good for this, but haven't tried it.)
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