I've recently grubbed out a couple of bramble (blackberry) bushes and have about twelve square feet of border waiting for something to go in. They were self-seeded and it seemed a bit pointless keeping them when they grow wild in such profusion round here.
My first thought was another rhubarb crown and currant bush but, to be honest, we have more soft fruit than we can eat so I'm inclined to something more decorative than edible. I'd like something that will attract pollinating insects but be compact and manageable. We already have buddleia and other flowering shrubs so any thoughts would be welcome.
What is the aspect of the area and soil type? Did you want something shrubby, or perennials?
Here's a few random ideas: Viburnum bodnantense Dawn? Good for early insects. Or a mixed planting of lavendars, rudbekias, echinaceas, perovskias etc for some late summer colour? Grow an ivy and allow it to mature - there's one growing up an old tree stump in our neighbours garden and it is literally humming with insects at this time of year when it is flowering. I assume you've already got a comfrey patch? You could plant a little tree if it wouldn't shade your veggie patch - I love amelanchiers. I've got two that I planted early in the year and the autumn foliage is fabulous.
Agree with other suggestions and would add some Sedum and early spring flowers which will come up and disappear on their own like crocus, snowdrops, pulmonaria (sp?) and bluebells if its shady - invaluable for the bumblebees that get caught out by a few sunny days early in the year and come out too soon.
Have had masses of insects in a plug-planted patch of tussocky grass in our garden - put in Vipers Bugloss, Echinacea, ox eye daisies, Mullein, all plastered in insects, many of which I'd never seen before. Another patch just has garlic mustard and ramsons, early edible salad for us, little haven for orange tip butterflies.