Brown recluse
They are called White-Spotted Brown spiders
a redback spider
A garden orb weaver probably
Is it a white orb? In that case it would be an egg sack. If it is actually a white spot it cold be a wolf spider. I am sure another user could provide a more detailed answer but I have seen wolf spiders with white spots.
The worst kind.
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The spider you are describing sounds like the bold jumper spider (Phidippus audax), which is commonly found in Northern Indiana. They have a distinctively marked brown abdomen with white spots and black and white striped legs. Bold jumper spiders are known for their agile jumping ability and are harmless to humans.
An Arrowhead spider is brown with a green back. This spider is also known as a Triangle Orb Weaver. This spider is not venomous.
a tarantula!
Spiderman's Uncle
If this is a relatively small spider, then I would suggest that it is a Jumping Spider, and more specifically, possibly a Daring Jumping Spider. Read about Jumping spiders at the below link...(and sorry if this is not what it is.)http://au.answers.yahoo.com/question/index?qid=20071107223852AAzJ1vz
That sounds like a common garden spider. They are a low-venom spider, usually shy and spin an orbital (round) web, the kind that are often photographed with dew on them. They live until first frost and are generally thought to be beneficial.