Captain Blood mentioned the Village Green resin ships, the largest of which is a real beauty. Those are supposed to be available now from Stronghold miniatures in the UK, but that company is on a temporary shutdown due to a family breakup, according to the web site:
http://www.stronghold-miniatures.co.uk/I want to make some slightly more specific recommendations:
Everybody has recommended good sources for pirates. However, when taking on this topic, it's good to look for merchant ship crews, local defence forces, townfolk, natives/cannibals, and wierd stuff like skeletons to fill out the whole pirate scene.
Regular male pirates: as recommended above already, but add in Brigade Games.
Early types for the 1500's: Foundry's El Dorado and Elizabethan sea dog packs.
Duelist types (as in 3 musketeers): Blue Moon, Brigade Games, Black Hat.
Female pirates: Bronze Age (my favorites in a "Victoria's Secret" style), various figures scattered throughout the Reaper, Foundry, and other lines, with special mention going to Brigade Games
Arab pirates: Foundry Zanzibari and Baluchi packs, Reaper for a few character figures.
Chinese pirates: Foundry, some Pulp Figures packs (without modern weapons), Old Glory.
Townsfolk: Foundry (Mexican peasants, 18th Century civilians, and monks), Old Glory pirate line
(bar scene pack, Governor's pack, and victims pack), Old Glory horror lines such as the Sleepy Hollow packs, Front Rank civilians, Reaper townsfolk packs (some figures too medieval, but other's useful), Blue Moon 18th Century civilians box set.
Marines: most troops on ship would be like the land troops, but the British ones wore a short cloth fusilier cap that can be found among the lines below, including Foundry, Dixon, and Old Glory.
For local defense forces: Dixon's Augsberg and Grand Alliance lines, Perry's Glory of the Sun line, Foundry's early Marlburian packs (informal tricorns) or English Civil War or Thirty Years War packs for the 1600's, or you could use various tricorn wearing lines for early 1700's, including Front Rank (big figures), Foundry, Dixon, or Old Glory (cheap but nicely animated). For 1500's use Foundry.
For merchant ship crews: Old Glory European sailors.
For natives/cannibals: Copplestone (Tupi, etc.), Old Glory cannibal packs, and various Foundry.
For skeletal or undead pirates: Moonlight Minis, Eureka, Reaper, and the Old Glory undead crew.
For ships, I think the choice is between using smaller ships, usually resin or wood, to set the scene, or using larger ships so that one can fight big melees on deck. Many resin ship makers have been suggested, but for the bigger style of ship, the best bets are (1) Playmobil, (2) Mega Bloks, or (3) scratchbuild your own (such as with the Gary Chalk designs). The Mega Bloks ships require a bit more conversion work due to all the little bumps, but the results can be fantastic. See the thread on the Avery's treasure game posted by Sinewgrab recently to see what I mean.