N Connectors are usually found on external antenna and antenna cabling. It's usually cheaper to make your own cabling from RG-213 or LMR-400 cable and a couple of N-Connectors, than to buy fixed length cables from your Access Point manufacturer.
Male RP-TNC
Female RP-TNC
<tr>
TNC connectors are usually found on access points such as the linksys WAP11.
Male RP-SMA
Female RP-SMA
<tr>
SMA connectors are usually found on PCI wireless cards, such as the Belkin F5D6001 or the Netgear MA311.
Male MC (Lucent) Connector
Female MC (Lucent) Connector
<tr>
These connectors are usually found on pcmcia cards like the Buffalo WLI-PCM-L11G.
The 'RP' in RP-TNC and RP-SMA stands for Reverse Polarity. Hardware manufacturers seem to love using connectors that are hard to find. Most commercial converter cables and pigtails, convert the antenna connector to an N-Type connector, as almost all external antenna (yagi,omni or patch) come with N connectors.
If you need to make an extension cable between the antenna and the pigtail/converter cable, we recommend using either LMR-400 or RG-213 cable as these are durable low loss cables suitable for 2.4 Ghz.
Thanks go to Mark for his correction on the RP images