First, turn on Icon Preview. (basically, like Thumbnail view in Windows)
Go to Icon View.
View > Show View Options (shortcut: Command J)
Check "Show Icon Preview"
Resize the Icon Size as needed.
note: You can show Icon Preview on the Desktop too!
Second, if you want to be able to browse the pictures in a folder in a Previous/Next fashion,
download the Xee image viewer:
http://wakaba.c3.cx/s/apps/xee.html
Yeah, I know you said you didn't want to get an app, but Xee's a very good application. I
highly recommend it.
And you can customize all the keyboard shortcuts too.
(By default, the <-- and --> keys are not mapped to Previous and Next, but you can easily set it yourself.)
Personally, I don't like how iPhoto works either. (the whole "importing and organizing in albums" thing)
I prefer to organize my pictures by folders and view them using Xee.
Third, you can also sort of browse the pictures in a folder in Preview, though it takes a little effort.
Select the pictures you want (or Select All), then drag them into Preview.
It should open them in the drawer of a Preview window.
You can then use the drawer to navigate.
Fourth, you can do a Slideshow from the Finder.
Like the Preview trick, selecting a bunch of pictures (or Select All),
then right-click them and choose "Slideshow."
However, functionality is rather limited.
(not to mention there is a limit of 100 pictures for some incomprehensible reason)
Use this one if you absolutely don't want to use an additional app.
