I think social network spamming has become much more popular, I wonder if this also has had an effect as people leave traditional email spam (or don't worry about replacing it when governments shut them down).
I never really understood why pagination links expire. Most sites don't expire, you just have to deal with knowing that content that WAS on page 3 when you loaded page 2 might have changed.
Our AgileTask (http://agiletask.me/ , shameless plug!) team just had a giant brainstorming session on how to try and get more traction.
We did the simple rule of "no but's, just and's" (every idea someone has to say "and" to, no shooting down ideas, saying "but" or debating them at all until you are done brainstorming) and came up with a giant whiteboard of possibilities for us to try out.
Our next focus is going to be community engagement. Look at the people using your app and try to be a genuine member of that community. Things like commenting on hackernews (weee!), writing blog posts about productivity, commenting on similar blogs, etc. Just be genuinely helpful, honest, and don't spam.
Also look at generating content for related projects. Try and find podcasts to be a guest on, ask a blogger if you could write a guest blog post, etc.
Either way keep your chin up and keep on trying. Don't let one competitor burst your bubble.