I absolutely love the simple and clean interface and features that iPhoto and Aperture bring and I absolutely hate the "library/import" approach. I like to see my photos as files on a disk and that's that. Is it possible to just navigate through a drive in iPhoto and open images for editing or do I always have to import stuff?
You have to do the imports. The systems need to set up all of their information about the images somehow, after all.
So, start the imports and go do something else for a while. You're not required to sit and watch the imports. Let the computer do its thing, and then come back later when it's done.
Although storing your photos in folders is fast and simple, you can't place one photo into two folders without making file duplicates. And thus locating the necessary images might require more time.
So economy in a stage of image library classification will leads in loosing time in finding images later.
I am with you entirely. I hate having to do an import. I don't mind pointing an application at a folder that I have laid out. I can further sort within the app, add tagging, etc. But it had better not move my photos around.
I don't know of any way to do what you want with iPhoto.
Lightroom does indeed support a "folder" approach where that folder and everything under it is in the app for you to work on.
Aperture yes as "referenced masters" — iPhoto no, it only supports its own library structure.
Aperture allows you to import photos as "referenced masters". You can do this from the import settings under the "Aperture Library" settings, by setting "Store Files" to "In their current location" (if already on your hard drive in your own storage system), or by selecting the appropriate folder for your folder-based-library. Note that you can also use the "Rename Files" setting to set up sub-folders (e.g. "YYYY/MMM/DD") as well as renaming the files as they're copied to the folder-based-library.
The same setting exists for "Import Folders as Projects" if you already have a project-based folder structure for your master photos.
Note that only the masters are getting stored in this structure, so you'll still need Aperture to browse your modified/processed images (unless you export to another folder structure).