One of the biggest surprise when you come into the Mac world from the outside is how obsessed the heavy-duty Maccers are with doing things with keyboard shortcuts. Given that the Mac popularised the mouse, it's rather amusing that Macfans just love to do as much as possible without ever taking their hands off the keyboard. Now this works quite well for me - in Windows, I always used to cut and paste using keystrokes, for instance. But when it comes to the Mac much more seems frequently done this way, and there are plenty of helper apps like Alfred to extend the possibilities.
Liquid is a productivity tool for people who often look things up - ideal for a writer. Let's say I'm writing about Jupiter and wanted to check a fact in Wikipedia (yes, it is possible to do this - the science coverage is usually very good). I've just typed Jupiter in Word (say). All I do is highlight the word Jupiter and hit Liquid's activating key combination followed by RW (short for Reference Wikipedia). Zippo zappo and Wikipedia opens on the page for Jupiter.
|At the point I've typed Cmd-§R but not the W for Wikipedia|
I can equally look things up in (say) a dictionary or Wolfram Alpha, can search the likes of Amazon and Google or can do an instant conversion, say from Celsius to Fahrenheit (something I do quite frequently). This takes a few more key presses, but it's still just select, activate keypress then C(onvert) T(emperature) C(elsius) F(ahrenheit).
It is brilliant. All that I have described so far is in the free version, but I've gone for the paid for 'Pro' version, partly because I think it is worth £2.99 and only fair to pay for it, and partly because this adds translations and the ability to include your own searches. So, for instance, I can now search Amazon.co.uk as well as Amazon.com, can reference the full OED, which I have online access to, rather than the the cut down dictionary, and can make use of my own www.popularscience.co.uk site (or this one).
The app's not perfect - in fact it can be rather frustrating. The default key press is Cmd-@ (for Windows users, Cmd is the equivalent of Ctrl in keyboard shortcuts). But @ is a shifted character, so it takes three fingers to do. I have switched this to Cmd-§, which is just two keys, so practical with one hand. But changing the setting isn't as easy as you might think, as you have to do it in the Mac's services control panel, as Liquid has to act at a low level to intercept keypresses. The other irritation is that occasionally the key press does nothing, and occasionally the text you highlight isn't copied into the app. You can still type what you are searching for, either calling up the app with the keypress or using its little toolbar thingy - and sometimes that is better because you might not have typed the text you want to look up - but it is a real pain when it doesn't work, as to be efficient, you want to type the control keys without needing to check the word has passed through.
Despite these minor moans, though, it's a real winner.