I'm reading a book right now about intensive gardening methods and in this book is a list of spacing for most vegatables. About peppers the book mentions 12" apart as the closest.

I have a bed that is 4'x8'x2' and in it I have something like 20 pepper plants all spaced 12 inches apart, except the ones closest to the edges, which are all 6" away from the wood. This is my first year gardening, and I don't know if in reality this is too close, but I guess we shall see.

My husband also built me a raised garden (4 ft x 7ft) which is smaller than yours. We have 17 plants in it and all are thriving. Our broccoli and cauliflower are getting a bit crowded, but so far they aren't competing for light. Maybe we planted too much, but I'm not going to worry about it.

All of my garden area is raised garden beds. I tried to plan accordingly. For example, I planted my squash with my peas in one raised bed (which is 30in x 66in). The pea plants will be done before the squash is ready to produce squash on a large scale. The two might be conflicting a little right now, but that problem will soon cease to exist. I did the same with my sweet potatoes and kohlrabi. I expect to harvest my kohlrabi in the next week or so. Then the sweet potatoes will have the bed all to themselves.

I live in the city on a city lot. My yard isn't the biggest so I have to make use of what I have. Raised gardens have done wonders for me.

Here is a link to view my raised garden beds if you want to see what I did.
http://www.flickr.com/photos/veggiefaery/

Keep in mind...the closer the plants, the more chance for pest/disease no matter how well they are thriving because of how on-top of the water/nutrient needs you are.

For instance, sometimes it's worth it to put 5x2 or 6x2 tomato/pepper/similar plants in a 10-11x4 space rather than going for 7x2+ unless you're willing to spend the extra time multiple times a week scouting for stress/disease/pests.

If your beds are in full sun, you get a decent amount of days with wind/air-circulation, and you have good control of your irrigation/rain during the season...it's not much of a concern to crowd them a little as long as you manage the pests and keep an eye out for disease. If the situation is less than ideal it can take a little more work.

That said, I personally crowd some stuff because I do spend time in my small garden 4-5 days a week scouting for pests and disease. Some stuff (like squash) I would never crowd because of our local humid summers and my own garden micro-climate which makes it prone to both powdery mildew and squash borers.

...and of course there's always a limit to how much you can crowd different kinds of plants before they suffer from lack of root or canopy space.

The squash plants are taking most of the room. They are space hogs but usually produce lots of veggies. Take a look at the square foot gardening forum for ideas on plant spacing in intensive gardening. There's a link below. Lots of good information there.

One of my raised beds is 4' x 7' and it has 2 basils, 7 peppers, 4 sq ft of kale, 3 sq ft of onions, 5 cucumbers, 5 tomatoes, and a couple of square feet of marigolds. The cukes and tomatoes are on trellises. And this is not planted as intensively as it could be.

Another slightly larger bed as beans, eggplants, more cukes and tomatoes, and one huge squash plant. The squash is set in a corner so the largest portion of the plant is spilling over into the area beyond the bed.

They are just my examples of intensive raised beds. You can plant much more in yours than you already have and still have room for them.

Good luck.
Sandy

Here is a link that might be useful: Square Foot Gardening forum

My bed is 2 foot x 18 foot and it is thriving !! ... I have the following in it ...
2 Cherry Tomatoes
6 Tomatoes (2 ea. Better Boy, German Johnson, Homestead)
2 Bell Pepper
2 Yellow Squash
1 Zucchini Squash
2 Cucumber
3 Cantaloupe
2 Watermelon
2 Eggplant
5 Sweet Potatoes
12 Bush Beans (with room for 12 more planted in another week and 12 more planted in 3 more weeks)
---
27 big plants + 36 bush beans
... plus 10 dwarf Marigolds, and 4 Petunias
... and Nasturtiums around the outside of the bed

Read the following FAQ section for info on how to do this ... http://faq.gardenweb.com/faq/sqfoot/

As has been suggested you can get a lot more into raised beds than what you've listed. I have 3 beds, 4x12 each (20" tall) and get a LOT out of them (I do 15-20 'maters in separate containers). As an example, half of one bed is dedicated to herbs (which are permanent residents due to being perennial here except basil) and the other half to peppers (this summer...it was broccoli/cauliflower/collards last fall/winter)... in this bed we have a 1x4 area of oregano, 2 rosemary, 2 sage, 3 thyme, and 4 basil (which is more than enough herbs for us and to give away)...then I've got 12 peppers in the other end of the bed, all spaced about 15" apart in a grid...and there's still a 2' wide gap in the middle where I had a couple of row of garlic. In another bed, I've got 5 squash/zucchini in half a bed and suspect they'll take up all that room plus some more if the SVB don't get 'em...the ohter half of this bed had about 175-200 garlic until June 1, now it's empty and awaiting fall crops. Check out the square foot gardening book (Mel Bartholomew) for some ideas...or just do like I did and experiment for a couple of years until you get it figured out. And like nc-crn mentioned, the closer you plant, the more vigilent you'll have to be re: pests/disease.

I have 2 beds that are 4x12.

In one bed I have:
6 toms
1 pepper
1 squash
3 melons

The other has:
4 toms
3 melons
Beans
Arugala
Spring lettuce
Garlic chives

Squash takes up huge amounts of space so I chose a more compact variety. Melons also take a lot of space so I either trellis up or let grow over side of gardenbed onto ground below.

Pics in link below.

Here is a link that might be useful: pics of 4x12 raised garden bed