The genus Grevillea is a member of the Protea family, and family best known for Protea cynaroides- the 'King Protea' (the national emblem of South Africa). However, unlike Proteas the Grevilleas are hardy(ish) (but dislike extreme/prolonged cold). The individual Grevillea flowers can almost be likened to a tiny prawn (if you stretch your imagination!), and the stigmas stick out, giving the flower cluster a slightly bristly look. The flower clusters are typically pink/red and quite strongly coloured, although I know a deep orange, and paler pinks can also be found.
Grevillea lanigera- this shrub grows outside in an open spot here in Cornwall. Most of the Grevilleas I've seen have needle-like leaves, but G. victorinae (below) has larger silvery leaves.

This Grevillea is grown outside in a sunny but sheltered spot at RHS Rosemoor and has become a large shrub. The flower clusters are larger than other Grevilleas I know, and I love the warm orange colour. Grevilleas are usually thought to be half hardy/tender, and to a certain extent they are. For most of the UK the smaller varieties would be suitable for a cool conservatory or greenhouse during winter, but Roy Lancaster first met G. victoriae in a sheltered spot on a Midlands nursery, so Grevilleas may be worth trying outside against a warm wall. If you prune Grevilleas they will grow more compact, and also they seem to flower better.

The Grevillea 'Canberra Gem' below is growing well on top of a traditional Cornish wall- a double layer dry stone wall infilled with soil and stone. The shrub has grown to about 10ft (3m) tall and wide, and has not been given any supplimental water.

This neglect seems to suit Grevilleas well. One really important thing to remember is that you must NEVER feed a Grevillea- all members of the Protea family are intolerant of phosphates, and even high nitrogen feed has enough phosphate to harm a Grevillea.

I stumbled over Grevillea juniperiana f. sulphurea at RHS Rosemoor in the old tennis court. This warm and sunny spot has particularly good drainage, so suits Grevillea well. Based on the Rosemoor plant I would not recommend this for a tiny garden, it must have been 10ft tall by 15ft wide (approx 3m by 5m)!  Want to know more? Try this article from the National Collection Holders at Pine Lodge Gardens: