I tend to use the standard paintbrush, or sometimes pencil at around 5 to 10 pixels (depending on the dimentions of the piece) for touch up and drawing, but using a tablet, I can vary my pixel width without changing the width all the time. This is just where I seem to like it. The more specilized brushes seem to be better for coloring, shading, and adding effects later.
I tend to work in 300dpi at least, and use a 5 or 3 pixel hard brush at first, then finer for more details and I zoom in a LOT to make smoother lines. I'm not sure why you don't want to downsize piccys, it tends to smooth things out and gets rid of those 'bit errors' you're bound to get.
I tend to also work at 300dpi, and most of my images are 8x10in or larger in size. Working at a standard resolution (72dpi) and just using tiny brushes is asking for too much headache as even the hardest brushes (aside from the pencil tool) will be a bit fuzzy, unless you do a lot of work to crisp them up. (Either by filter or by erasing edges.) This is even more of a pain if you're working with a mouse, and not a tablet. (yummy, yummy tablet)
That said, if you want uber crisp edges at a small size, try out the Pencil tool. No anti-aliasing there, and the hardest edges you can imagine. (Perfect if you are into pixle art anyway.) Or if you're really, really, really patient, try using the pen tool to outline all your lines, and then stroke the paths.
@Liz!
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"...I want to be able to draw the images at 100% their size (that is, just draw and save, no resizing)..."
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Lemme ask... why not resize?
Drawing actual size is significantly harder because of the uncontrolable errors the computer can cause, and controlling each and every pixel is harder than herding cats. If you don't want to go up to 300 dpi, dry drawing at 150 and then sizing back down to 72.
Seriously though, you should resize down. Images look SO much better that way.
Whhops, during a rewrite of my post I forgot to mention that this sorta thing would be for a black and white comic, rather than say, a big picture... for those I do make things bigger...
The reason I don't want to resize it, is because I find doing 5-8 panels each at high rez, then scaling it down and slotting it into it's box, takes loads and loads of time, where I'd rather just draw into the box directly at normal size...
Even newspaper comics draw at a bigger size then scale down y'know :P
Do like this. Make a -large- canvas, draw on that 'in the box' for everything, then when you're all done, batch resize them all to the size you want :P done! 
I make my own brushes and edit available brushes... so I'm not much help
I normally play with shape dynamics and opacity on actual brushes, and make my own for shading.
I also jump between Photoshop and Painter...
I was wondering what everyone's recomendations would be for Photoshop brushes would be.
I want to be able to draw the images at 100% their size (that is, just draw and save, no resizing) and was wondering what would be a good brush for this, I find the standard brushes have to much anti-aliasing...