Candidates

I thought it about time I listed some of the sites I'm yet to join, or am expected to join but not yet mentioned.

Paddy Power, William Hill, Totesport, VCBet, BetDirect, BetHiLo and Coral have already been joined before the experiment started.

I cannot find the details and Ts and Cs of the free bets for bet-at-home.com, PartyBets, bwin, Spreadfair, GameBookers, IASBet and Mansion.
Update: bet-at-home.com 100% bonus, but deposit and bonus must be wagered three times before withdrawal.
IASBet $100 bonus for a $50 deposit, but free bet winnings must be turned over two times in full before withdrawal. Email from the company regarding deposit requirement and possible association with Canbet:
"Just to confirm you may claim this offer and you will need to deposit 50GBP thank you."

Bet24 will give a £30 bonus for a £60 DEPOSIT (not bet). The catch here is that this bonus MUST be wagered at odds of at least 1.5 four times before a withdrawal can be made.

BetSafe will give a £20 bonus for a £40 DEPOSIT (not bet). Similar catch to Bet24 in that the bonus must be turned over at least 10 times before withdrawal.

BetUK will give a £25 bonus for a £25 DEPOSIT (not bet), but the catch here is that to get the bonus, you have to place bets totalling £100 at odds of at least 2.0, and the bonus must be bet through three times.

expekt.com will give a 100% first deposit bonus up to £25. You have to email them with your customer number and deposit amount to get the bonus. The deposit AND bonus must be turned over at least three times at odds of at least 1.50.

intertops.com give a £10 free bet for a £10 deposit, but - get this - the free bet must be rolled over at least 16 (sixteen) times before it can be withdrawn.

Interwetten is another site with a multiple wager clause. They will give a £30 bonus for a £60 deposit, but you have to wager the total deposited, including bonus at least five times at odds of at least 2.0 before a payout can be requested.

Lasseters also have a multiple wager clause. £30 bonus for a £120 deposit, but you have to wager the full deposit AND bonus three times before a withdrawal is permitted.

Unibet give a £10 bonus for a £10 deposit, but require that you turn over the bonus amount six times before a withdrawal is possible.
Update (Tuesday, 23 September): I can't find the bonus details on their site any more.

WinUnited give a £25 bonus for a £50 deposit, but the deposit and bonus must be turned over five times before withdrawal.

BetFred, CentreBet, MyBet, Stan James, Sunderlands and Boylesports do not have a secure registration form.

Good candidates:
Betway is a no hidden clauses £25 matched free bet site.
Update: Betway have a 1.75% fee on Credit/Debit card deposits.
Eurobet gives a 20% bonus of the first deposit up to a maximum of £20 (so £100 deposit required). You need to quote AFFWIN during the registration process. What is unclear and will need to be investigated is whether the bonus will be paid even though I'm already a member of the partner company Coral.
Update: Email response from Eurobet "We would like to inform you that even if eurobet and coral are sisters sites the promotions they offer are not linked between them."
Ladbrokes will give a £10 free bet for a £10 wager. Information cannot be found directly on the site, but via affiliation links. I will check with their customer support if it is valid.
Update: Email response from Ladbrokes "I can confirm that free bets are credited upon the settlement of your qualifying bet."