In reply to mypyrex:
IMHO the best place on the curry mile is the Punjab. South Indian food, and used to be 100% veggie. They do all the standard curry house dishes, but you need to look beyond them. They do fantastic thalis where you get lots of little dishes and the dhosas are awesome. My fave is the paneer tikka starter, big lumps of paneer done in the tandoor.
As a general rule of thumb, any place with lots of brightly coloured sweets in the window is a good bet. At least one person can cook, as can be seen from the sweets. As they serve the local asian population with authentic sweet treats, their curries and samosas are usually good as well.
Notable mentions go to Tib St curry houses, there are several in that area, This 'n' That included, but I prefer the Yadgar for rice and 3.
If you're in London, Drummond St next to Euston is great for veggie south Indian food. If you go at lunch time there are 3 places that do a good buffet for a reasonable price.