How to resize multiple images?

I've recently purchased a Nikon D3200, and I've been taking all my shots in 24mp just so I can blow them up or crop when needed. I was wondering however if there's a way to resize 100's of these images to 6-8mp, as the files are simply too large to keep storing and become slow to work with in photoshop or to browse though sometimes.

I use Adobe Lightroom 4

You can batch process RAW files and export them a reduced size and resolution JPEG files.

As far as storing image files, you really need to save them at the highest resolution possible (RAW).To keep your hard drive from filling too fast, you can do what many of us do and that is to use 4 gb cards and when copying all the images files to the computer, burn a DVD as backup, so you never have to worry about losing your originals. We also use an external hard drive. You can buy a 1 tb external drive for under $90

You spent a lot of money to get a camera with a high resolution sensor. Neutering the resulting images is really counter productive

Don't do it - don't resize originals! Storage is cheap these days, and with a decent computer, Photoshop can handle those files perfectly well.
If you are absolutely determined to work only with small files, then at least backup an original and resize a copy. That way you can come back to them some day in the future when you have upgraded your computer and changed your mind about something.

How to batch resize? You say you have Photoshop, so you could use Bridge to batch resize via running an action. I believe there are other ways, as well, but I don't use Photoshop for resizing.

I use a very simple little "power toy" with my Windows computer: http://imageresizer.codeplex.com/

ETA: there are oodles of tutorials around, here is one of them: http://digital-photography-school.com/how-to-batch-resize-in-photoshop

Many photo editing programs have a batch process, wherein you can make a change to multiple files.

I use the free program, Picasa, by Google. One of the neat features allows you to tag a large selection of photos, then "export" copies of them to a newly created folder, at the size you select. I use that feature when I have a ton of photos taken at 12 or 16mp, and need to upload them to my editor at a much smaller size. The bonus is that your original, full-sized photos are safe and untouched for future use.
http://picasa.google.com
http://support.google.com/...1944?hl=en

Http://keerok-photography.blogspot.com/2012/09/software-for-resizing-changing-dpi-and.html

How to get 6MP? You can use the program above to resize the pictures to 3072 x 2048 pixels in Batch processing mode. Just set once and go. Go out and take a coffee break then come back with your job done. As much as possible, always save to a new folder. Do not overwrite.

Store in their original size. You will never know when you will actually need those huge MP's.CD's are super cheap nowadays anyways.