I planted Marigolds next to both bush and pole beans this year (about four marigold plants to about 20 bush and 10 pole bean plants) and I had a major infestation of spider mites. I got a few weeks of good harvests, but eventually the mites spread throughout the entire crop and I had to pull them all out prematurely. Not sure if there is a correlation, but I recently read that this was one of the potential problems.

Some Marigolds (especially Mexican Marigolds) can have an herbicidal effect on some plants like beans and cabbage. For the most part though, Marigolds are fantastic for companion planting because of their natural pesticidal qualities.

Here is a link that might be useful: eGardenSeed.com

Last year I had a garden for first time, and planted lots of marigolds near pole beans, also planted borage and fennel and nasturtiums, and I had no pest problem, aside from the vine borer that wiped out my dakota squash...but that was my fault b/c I grew the squash very very late in season.

The only real problems you may have if the flowers are the 'mexican' type. Those can really harm herbs from the chemicals they put into the soil. However the 'french' and normal 'tagetes' types.

Via wiki:
Marigolds are a wonder-drug of the companion plant world, invoking the saying "plant them everywhere in your garden". French marigolds produce a pesticidal chemical from their roots, so strong it lasts years after they are gone. Mexican marigolds do the same, but are so strong they will inhibit the growth of some more tender herbs. Certain Varieties of marigolds (Tagetes) can help manage eelworms (Root-knot nematode) when planted the year before[1].
Tagetes has also been found effective against perennial weeds such as Ranunculus ficaria (Celandine), Aegopodium podagraria (Ground elder), Glechoma hederacea (Ground ivy), Agropyron repens (Couch grass), Convolvulus arvensis (Field bindweed), Equisetum arvense (Field/Common Horsetail) and other 'starchy' weeds.

A bit off topic but borage can be considered the magic maker of the garden.

The only thing you really have to watch out for is that some moths [dot moth for example] tend to feed on the flower. Although the list I looked at does show a caterpillar worm larve similiar to the imfamous mater eater, the list does not mention beans , maters, or peppers; so you should be fine.

From the book "Carrots Love Tomatoes", by Louse Riotte,
"Planting with beans help protect against the Mexican bean beetle, while they help deter weeds and may be planted as a crop against invasions of ground elder, bindweed and ground ivy. The older types with strong odor in both foliage and blossom are considered the most useful."

The link for "Carrots Loves Tomatoes" on ebay did not work, but they have it at a good price if any are interested...