My tomatoes pollinate if I just give them a good shake every day.
As for cukes....I plant the self pollinating varieties.
Otherwise, I think they have to be hand pollinated.
I think the idea of controlling pests by letting other insects in is wishful thinking.
Just my personal opinion developed from my own experiences.

Thanks for the advice, I would have never thought to shake the tomatoes.

I just send my personal pollinator (my 13yr old daughter) in with a soft small paintbrush and have her gently twirl it in each blossom. This will work on any thing that does not need cross pollination. I keep the brush tip in a baggie when not in use, that way I will always have some pollin on it and it stays clean and dry. I figure that over time there will be al sorts of pollin on it and maybe even enough to use to cross pollinate as well.

Mike