So after finishing RTK I started reading and writing sentences. Not having to type everything myself is a great help, but there's one catch: importing the spreadsheet as it is left me with huge cards. Sometimes up to three sentences in one card. That's way too long. However, sorting everything out manually would be a real pain, so I thought I'd have to program something that does this in a more automatic way. Well, the result is this. Keep in mind that I mostly programmed this for myself, so it's somewhat clunky and low on features, but it does the job (...mostly?). I'm also not really a programmer and just kind of hacked it together so it's rather ugly in terms of internal design (global variables), but it's not a big program and doesn't really matter when you're just using it either way. However, some people might find this useful, so I decided to just release it anyway in case someone is interested. It's written in Python with PyQt.

So before I go on, this is how it looks like in action:


Doesn't look too bad I hope.

How do you use it? This one's simple enough, but you have to keep some things in mind.
First you need a tab separated spreadsheet in plaintext. The one you get from Google docs when you export to txt works well. Then you can just start Cardsplit and open the file in the dialog that pops up and it will show you the first row of the spreadsheet in the text boxes. Like you see in the screenshot, there are 2 checkboxes at the top left. With those you can change the "split points". Basically Cardsplit will create a new line in the three text boxes for every "split point" character it finds. You can toggle them on and off as you wish. By default only . 。 and so on are activated.
So how does the splitting work?
Yes well, Cardsplit will read the first line of the spreadsheet, and display the first three columns in the text boxes with a new line after each "split point". You then edit everything as you wish and click next. Each line will become a card on its own. You just have to make sure that each text box has the same amount of lines. Other than that you're free to do as you see fit. I often edit my cards heavily and cut out useless parts for example. After you click next, the second line of the spreadsheet will be displayed and so on.
Then there's this "Keep comma" thing. If you decide to use commas as split points you can enable this and each line after a comma will have a comma inserted at the beginning so you know it was part of a larger sentence. Just look at the picture.

This might sound more complicated than it is, or maybe not,  just try it out and you'll see.

I suggest you only check the Comma box when you see a sentence you want to split on a comma. If you keep in on it will often cause the lines in the boxes not to add up when commas are or aren't used in both the translation or Japanese sentence. Other than that it will be pretty much automatic if you don't care about further editing with few exceptions like "Mr." or things like that.

Things to keep in mind:
- Cardsplit will DELETE the first line of the spreadsheet each time you click "Next". That way you can quit anytime and continue where you left off when you feel like it or need new cards.
- If your spreadsheet has more than 3 columns, the other columns will be appended to all created "subcards" (of the same row) as they are. This can be useful for notes and the like.
- Cardsplit will create a file "out.txt" in its directory. This is where everything will be written to. Import this into Anki.
- I've been using it for a couple of days now and I didn't find any real bugs left, but that doesn't mean they don't exist. Just import your cards as soon as you're done so you don't lose your work in case something goes wrong and you should be fine and (maybe) tell me about it so I can look into it.
- There's probably something I forgot...

You can download it here:
Source (Linux/BSD/*nix): http://www.mediafire.com/?uzsdzy99ifv
Binary (Windows): http://www.mediafire.com/?hhyggygrb0x (didn't test this for long, but it worked fine for me)
On OSX you'll have to use the Source and run it through Python. I think it's installed by default, you just need to get PyQt.