It seems like the original poster:
1. wants to use the services other Bitcoiners provide in maintaining the network, but isn't willing to pay a fraction of a cent in fees, and
2. wants to help others by relaying and including transactions that include no fees.
1. There are good reasons for fees. The main one is spam, I could send 100,000,000 micropayments for 1BTC, and every node on the network would have to relay and store them forever.
2. The mainline Bitcoin client will not relay transactions to others if they look spammy, and they will not get included in a block if they don't have an appropriate fee.
Transactions need to have a priority above 57,600,000 to avoid the enforced fee in the official client. Transaction priority is calculated as a value-weighted sum of input age, divided by transaction size in bytes:
priority = sum(input_value_in_base_units * confirmations)/size_in_bytes
For sending 0.05 BTC (5,000,000 base units) from one address, in 225 bytes (a minimal size, a one input, one output transaction with no remainder)
free when confirmations > 57,600,000 * 225 / 5,000,000 -- 2,592 confirmations
Having Bitcoins from multiple payments fund the transaction is where the "sum" in the formula above comes into play.
You can see above, the newer the coins are to you, and the smaller the amount is you are sending, the longer you will have to wait to send without fees. Sending microspam without fees will need coins older than Bitcoin itself.
There are some unofficial forks of Bitcoin that allow you to send without the expected fee, this will probably result in a lot of headache when you try to send no-fee payments, they never get there, and you have to manually remove the bad transactions from your wallet with third-party utilities to get your balance back.
If you want to "help" free transactions get included into blocks, Eligius mining pool has the loosest rules about including free transactions; often no-fee transactions, that would otherwise be dropped, will be included when Eligius generates a block. You have to have dedicated mining hardware and software (video card rigs) in order to contribute substantially to mining though.
It's really not an issue though, is it? About any transaction you would want to send will be .0005 BTC (about 1/5 of a cent). Paypal charges $0.35 + 2.9%.