As a computer scientist, I am especially concerned with electronic ballots and electronic voting machines. Electronic votes can be hacked and changed in undetectable ways. While there is no such thing as a 100% secure ballot, electronic ballots are far less secure than paper ballots.
I like machines. I like electronics. Computers are neat, they can make our lives easier. Computers are especially wonderful for Americans with disabilities. Computers have their place, and their limitations.
In my ideal scenario:
Voters would show up to the polling place;
Present positive identification;
Be confirmed as a valid voter that has not yet voted in this election;
Be presented with a paper, fill in the bubble style, ballot;
Choose either a normal voting booth or an electronic assist booth;
For a normal booth they use a pencil or pen and fill in the bubbles to select their votes; OR For electronic assist, the feed the ballot into the machine, select their votes using the machine inputs (touch screen or keyboard, etc). They review and confirm their votes. The machine marks the ballot with their choices and ejects the ballot.
Either method, the voter can now review their paper ballot, if there is an error, exchange the ballot for a new one;
Once finished, they may then cast the ballot into a ballot box, which may or may not have an electronic reader built into it.
Rules for ballots:
Ballots must be standardized, look similar from precinct to precinct and to sample ballots available weeks prior to voting day and posted at the polling place. People should not be surprised or confused by the appearance of the ballot.
Ballot must be clearly legible and human readable without separate cyphers or keys. No hanging chads, confusing look-up tables, codes, or other obfuscation. If a fourth grader cannot look at a ballot for 15 seconds and correctly tell you for whom the vote was cast, then there is a serious flaw in the ballot. If the ballot was cast using assistance from an electronic machine, the machine must mark the same paper ballot in the same way, as would a person not using a machine.
Ballot must be individual, not physically attached other ballots. Electronic storage of ballots are not allowed. Counts and totals may be recorded electronically, but recounts must always be able to examine individual paper ballots.
Ballot must be reasonably permanent, non-volatile, and tamper-resistant. Electronic ballots are not allowed, because the vote can be undetectably changed. The ballot must show evidence of erasing and tampering, whether by the voter or others. The ballot must remain legible in temperatures under 300F, in full submersion in water, or subjected to any normal or extreme condition that may be reasonably expected.