Thanks in advanced.
Say you have a maze, and a mouse. The mouse, denoted by an uppercase 'M' character, starts out somewhere in the maze. The mouse has to find his way through the maze, to the end.
To add a bit of spice, say there's a piece of cheese at the end of the maze, denoted by the letter 'C'.
A maze would be stored in a file on disk, called something like "maze.dat." The file would be a normal text file, with a maze drawn out in simple characters.
Here's an example: http://pastie.org/5721807
(You can create a more simple / complex maze if you'd like, or maybe find one online.)
So, you've gotta figure out an algorithm that the mouse can use to find its way out.
Tip: be sure to handle the case where the mouse can't find a way out (yet) .. i.e. the infinite loop case.
I hope this helps. Have fun!
Edit: switched to pastie.org link since hn didn't format the maze properly.
I remember having some fun with this one. I think the prof gave us a pretty simple maze, and a fairly complex one to test with. You may want to try the same, and start by solving the simple maze.
Other than that, the advice to try and solve a real-life problem is good.
Since you're currently working in the console, it may be a bit tougher to find some problems to solve. But here's a few ideas:
1) Write a program that can download a given webpage
2) Expand #1 by writing a library that allows you to parse the different HTML nodes on the page, searching for things like "a div with an id of 'content'"
3) Write a console based file uploader. I.e. so you can have a file in the root of a directory that you're working on, say "uploader.dat", which has the ftp (or ssh/S3?) server and username, and the files to upload / exclude. When you run your app, it will check that file, prompt you for a password, connect, and upload the specified files to the server. You can have settings in the file for whether to overwrite files or not, or prompt the user to decide whether to overwrite a file. You can add a bit of smarts in by checking the "last modified" date on each file, and compare it to a stored setting of when you last uploaded files (or each individual file). Perhaps display the files that were uploaded / modified after the upload is complete.
Anyway, just some thoughts. If you can find an app / problem that you'd be truly passionate about building / solving, I'd say go with that one.
I hope this helps.
Sorry - not trying to be rude but you've asked a silly question IMO. It's like someone picking up a guitar and then going around asking their friends, "What songs should I learn?" Hell, learn the songs you like and want to learn. You shouldn't need other people to tell you what you want to do.
When I made that, it resulted into great progress.
This site has a lot of interesting tasks in many languages. "100 doors" and "24 game" are good starters. "Minesweeper" (text-based) is a little more involved, but it might be what you are interested in. Sudoku games and solvers are lots of fun.
Making a text-based chess or go game (no ai) could also be an interesting challenge.
https://github.com/alexch/learn_ruby has some good challenges for Ruby, but I'm sure they can be done in other languages.
You can try writing a program that displays animations of different sorting algorithms (a nice way to compare the sorting algorithms). You can make the animations something like this: http://en.wikipedia.org/wiki/File:Bubble_sort_animation.gif
Also, you could display an animation for the Tower of Hanoi problem (http://en.wikipedia.org/wiki/Tower_of_Hanoi)
Try exporting the output as .gif and have fun.
A decent one for getting comfortable with graphs off the top of my head would be something along the lines of a peg board. Users can attach each peg to any other peg, and once you create a closed shape it fills the shape in. It would give you a good understanding of graphs, detecting cycle etc, and is not a trivial thing to do.
Takes you through writing an interpreter and then a compiler for a toy basic-like language.