SnapNames.com – Charged $69 but you only pay if they win the domain for you. You must order by 1:45 PM EST. If there are multiple bids, there will be a 3 day private auction held amongst those who backordered the domain with SnapNames.
GoDaddy.com – Only powerful if the domain expiring is with Godaddy (which can be checked using a whois lookup like www.who.is). They only charge $20, but refunds can only be used to place more backorders (credit).
NameJet.com – $59 with similar rules to SnapNames. There is a 12:00 PM EST cut off and there will be a 3 day private auction if multiple people backorder the domain through NameJet.
Dynadot.com – $15 with cut off 12:45 PM EST. 3 day private auction too.
Name.com – $49 but they refund you if they don’t get it. One backorder per domain, so there will be no auction.
DomainMonster.com – $65 after they get the domain.
Pool.com – $60 once they get it.
SnapNames, NameJet and Pool are the top 3 best domain drop catching services.